This picture will make you crazy..!!

Some Best Optical Illusions

Want To know about what causes Optical Illusions ?? 

Here is the answer

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What is the speed of electricity?

What is the speed of electricity ?

The speed of electricity really depends on what you mean by the word "electricity". This word is very general and basically means, "all things relating to electric charge". I will assume we are referring to a current of electrical charge traveling through a metal wire, such as through the power cord of a lamp. In the case of electrical currents traveling through metal wires, there are three different velocities present, all of them physically meaningful:

1. The individual electron velocity
2. The electron drift velocity
3. The signal velocity

In order to understand each of these speeds and why they are all different and yet physically meaningful, we need to understand the basics of electric currents. Electric currents in metal wires are formed by free electrons that are moving. In the context of typical electric currents in metal wires, free electrons can be thought of as little balls bouncing around in the grid of fixed, heavy atoms that make up the metal wire. Electrons are really quantum entities, but the more accurate quantum picture is not necessary in this explanation. (When you add in quantum effects, the individual electron velocity becomes the "Fermi velocity".) The non-free electrons, or valence electrons, are bound too tightly to atoms to contribute to the electric current and so can be ignored in this picture. Each free electron in the metal wire is constantly flying in a straight line under its own momentum, colliding with an atom, changing direction because of the collision, and continuing on in a straight line again until the next collision. If a metal wire is left to itself, the free electrons inside constantly fly about and collide into atoms in a random fashion. Macroscopically, we call the random motion of small particles "heat". The actual speed of an individual electron is the amount of nanometers per second that an electron travels while going in a straight line between collisions. A wire left to itself carries no electric signal, so the individual electron velocity of the randomly moving electrons is just a description of the heat in the wire and not the electric current.

Now, if you connect the wire to a battery, you have applied an external electric field to the wire. The electric field points in one direction down the length of the wire. The free electrons in the wire feel a force from this electric field and speed up in the direction of the field (in the opposite direction, actually, because electrons are negatively charged). The electrons continue to collide with atoms, which still causes them to bounce all around in different directions. But on top of this random thermal motion, they now have a net ordered movement in the direction opposite of the electric field. The electric current in the wire consists of the ordered portion of the electrons' motion, whereas the random portion of the motion still just constitutes the heat in the wire. An applied electric field (such as from connecting a battery) therefore causes an electric current to flow down the wire. The average speed at which the electrons move down a wire is what we call the "drift velocity".

Even though the electrons are, on average, drifting down the wire at the drift velocity, this does not mean that the effects of the electrons' motion travels at this velocity. Electrons are not really solid balls. They do not interact with each other by literally knocking into each other's surfaces. Rather, electrons interact through the electromagnetic field. The closer two electrons get to each other, the stronger they repel each other through their electromagnetic fields. The interesting thing is that when an electron moves, its field moves with it, so that the electron can push another electron farther down the wire through its field long before physically reaching the same location in space as this electron. As a result, the electromagnetic effects can travel down a metal wire much faster than any individual electron can. These "effects" are fluctuations in the electromagnetic field as it couples to the electrons and propagates down the wire. Since energy and information are carried by fluctuations in the electromagnetic field, energy and information also travel much faster down an electrical wire than any individual electron.

The speed at which electromagnetic effects travel down a wire is called the "signal velocity", "the wave velocity", or "the group velocity". Note that some books insinuate that the signal velocity describes a purely electromagnetic wave effect. This insinuation can be misleading. If the signal traveling down an electric cable was an isolated electromagnetic wave, then the signal would travel at the speed of light in vacuum c. But it does not. Rather, the signal traveling down an electric cable involves an interaction of both the electromagnetic field fluctuations (the wave) and the electrons. For this reason, the signal velocity is much faster than the electron drift velocity but is slower than the speed of light in vacuum. Generally, the signal velocity is somewhat close to the speed of light in vacuum. Note that the "signal velocity" discussed here describes the physical speed of electromagnetic effects traveling down a wire. In contrast, engineers often use the phrase "signal speed" in a non-scientific way when they really mean "bit rate". While the bit rate of a digital signal traveling through a network does depend on the physical signal velocity in the wires, it also depends on how well the computers in the network can route the signals through the network.

Consider this analogy. A long line of people is waiting to enter a restaurant. Each person fidgets nervously about in their spot in line. The person at the end of the line grows impatient and shoves the person in front of him. In turn, when each person in the line receives a shove from the person behind him, he shoves the person in front of him. The shove will therefore be passed along from person to person, forwards through the line. The shove will reach the restaurant doors long before the last person in line personally makes it to the doors. In this analogy, the people represent the electrons, their arms represent the electromagnetic field, and the shove represents a fluctuation or wave in the electromagnetic field. The speed at which each person fidgets represents the individual electron velocity, the speed at which each person individually progresses through the line represents the electron drift velocity, and the speed at which the shove travels through the line represents the signal velocity. Based on this simple analogy, we would expect the signal velocity to be very fast, the individual velocity to be somewhat fast, and the drift velocity to be slow. (Note that in physics there is also another relevant speed in this context called the "phase velocity". The phase velocity is more of a mathematical tool than a physical reality, so I do not think it is worth discussing here).

The individual electron velocity in a metal wire is typically millions of kilometers per hour. In contrast, the drift velocity is typically only a few meters per hour while the signal velocity is a hundred million to a trillion kilometers per hour. In general, the signal velocity is somewhat close to the speed of light in vacuum, the individual electron speed is about 100 times slower than the signal velocity, and the electron drift speed is as slow as a snail.

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10 Mind-Blowing Facts About Black Holes

10 Mind-Blowing Facts About Black Holes

 

Here are 10 interesting facts about black holes

1. It was John Mitchell who actually first proposed the idea of ‘dark stars’ or object. Later, in 20th century the term ‘black hole’ was coined.

2. Black holes are actually leftovers of former stars and are so dense that nothing can flee from their dominant gravitational energy. 

3. If the formation of a black hole has taken place, it can continue to grow by absorbing additional matter.

4. Generally the life cycle of most of the stars end up being a white dwarf or a neutron star, but, black holes are considered to be the last evolutionary stage in the lifetime of a star.

5. There are mainly three types of black holes namely stellar, super massive and miniature black holes, depending on their mass.

6. Since black holes possess strong gravitational force which pulls all of the light into its center, they cannot be seen.

7. Black holes follow the laws of gravity and hence in order to affect the earth, the orbit of a black hole would have to be very close to the solar system, which is not likely.

8. Astronomers are confident that our own Milky Way galaxy has a super massive black hole at its center.

9.Black holes have to hold a massive amount of mass in an incredibly small space to have the required gravity to pull light in. For example, to make a black hole with the mass of Earth, the entire planet would need to be squeezed down to a space 9 millimeters across.

10.When anything (be it planets, suns, galaxies or particles of light) passes close to a black hole, they will be pulled in by its gravity. If something else acting on the object, like say a rocket, is stronger than the black hole's gravity, it can escape the pull.

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Why does water freeze from the top to the bottom..?

Why does water freeze from the top to the bottom..??

The answer lies in a very peculiar property of water.  As you guessed, the density of water of water increases as the temperature is lowered, but below 4^oC this trend is reversed.   Here is a graph from The Physics Factbook. It shows the density of liquid water vs. temperature. The reason it can show liquid water below 0°C is that water can be supercooled, not actually turning to ice for a long time.




So what happens is the water that is just slightly above the freezing point rises to the top so the freezing process starts there.   This is the same reason why ice is at the top of a lake in the winter and not at the bottom.  This is beneficial to ice skaters as well as fish and other aquatic fauna.

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Does a fully charged battery weight more than when it's empty?

Does a fully charged battery weight more than when it's empty?

Yes because of E= mc*2
When you test the electrolite in a lead acid battery,as the battery charges the sulphuric acid becomes denser which gives it more mass so it "weighs" more.

Try it at home weigh a flat car battery on some reasonably accurate scales then charge it up and weigh it again.All you have added is potential energy.

The speed of light is constant,the energy has increased(it will start your car) so the only thing that can change is the mass.

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Interesting Facts About Earth

Interesting Facts About Earth

 

Earth is the place that each person calls home. It is home to over six billion people and around 8.7 million different species. While everyone lives on Earth, there are many interesting facts that people do not know about the planet. Earth is unique in our solar system as being the only known planet to support the multitudes of different life. Earth facts can reveal the true nature of the place life calls home.

The Earth is not a Perfect Circle

It was long thought that Earth was spherical in shape. After careful studies and measurements by scientists, it is now known that earth is more of an oval. If you look at the diameter from pole to pole, Earth is 7882.4 miles long. If you measure the diameter from the equator line, earth measures 7908.9 miles long. The reason for the difference is how the Earth spins. It spins on its axes, which goes through the poles, making some of its mass move away from the poles and to its outside center.

There are Few Craters on Earth

When Earth is compared to the Moon, it has less impact craters caused by space debris. The Moon is documented to have billions of craters, as can be seen by looking at it. The reason behind so few craters on the Earth is that Earth possesses an atmosphere, which creates fiction for anything coming into it. The friction caused by an object moving at hundreds of thousands of miles per second entering the Earth?s atmosphere causes the object to burn up before hitting the ground. The Moon has no atmosphere and cannot stop even the smallest meteor hitting its surface, which is why there are so many craters on the Moon.

The Earth's Atmosphere

The atmosphere around the Earth keeps the animals and creatures living upon its surface a great deal as far as the requirements of life goes. It weighs around five trillions tons altogether, which is calculated based on the atmospheric pressure it exudes on the surface. The pressure is around one kilogram per square centimeter. The atmosphere protects its inhabitants from harmful space objects like meteors by burning them up before impact as well as harmful light rays such as X-rays, ultraviolet light, infrared and gamma rays.

Gravity is not the Same Everywhere

v There is an area in Canada called Hudson Bay that has a lower gravitational force than other regions of the earth. Scientists believe that 25 to 45 percent of the gravitational flux is due to a giant glacier sheet that was in the area long ago causing the Earth's crust to subside somewhat. The rest of the reason behind the gravitational flux can be explained by down drag due to the magma in the Earth's mantle.

The place that all known living creatures live is a fascinating place. The Earth facts discussed in this article can give an idea of the type of place life call home. The most important thing that people of planet Earth can do is to look after Earth so that all future generations can experience the wonders that Earth holds.

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In the earth where the gravity of the earth becomes zero..?

In the earth where the gravity of the earth becomes zero..?

In a perfectly-shaped sphere, with a smooth surface, and composed of exactly the same substance with the same density throughout it, the force of gravity is zero at the exact center of the sphere. That does NOT mean that 'gravity becomes zero' at the center. It means that at the center, for every speck of mass pulling on you in any direction with any force, there's another speck of mass pulling you in exactly the opposite direction with exactly the same amount of force, so the whole thing adds up to zero. In the real Earth, we can't tell exactly where that point is, because the Earth is not a perfect sphere shape, It doesn't have a smooth surface, and we don't know every last little detail about the distribution of mass inside it.

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Can you have zero gravity conditions on Earth..?

 Can you have zero gravity conditions on Earth..?

Gravity will always be there, but you can set up an arrangement where you will appear to be weightless. Such an arrangement is in a plane that flies up and swoops down so that its path is a circle standing on edge. You will hang in the plane and appear to be weightless. What is actually happening is that for a few seconds the plane is falling at the same speed as you are so if you measured your weight on scales in the plane, you would appear to weigh zero.

Zero gravity is impossible on earth. Actually, zero gravity is impossible anywhere. Gravity acts through millions of light-years, holding galaxy groups together, so there's no way that you can eliminate gravity this close to a major mass like the earth.

However - you CAN have a situation that is mathematically and physically equivalent to zero gravity, and that is free fall. Jump on a trampoline, you'll spend a few fractions of a second in free fall, which is just like zero-G. NASA does it with the Vomit Comet, which is a modified KC-135 aircraft that flies in parabolic paths to give astronauts-in-training a free fall experience. 

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Some Amazing Facts Collection part 2

Some Amazing Facts Collection part 2

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1.The diameter of a proton is approximately 0.000000000001 mm (1/25,000,000,000,000 in).
2.The lightning bolt is 3 times hotter than the Sun.

3.If an item moves very, very fast, it becomes smaller and heavier.
4.The bark of the redwood tree is fireproof.
5.The Atlantic Ocean grows at about the same rate as your fingernails.
6.Lightning strikes about 6,000 times per minute on our planet.
7.The sum of the digits of a number which is a multiple of 9 is always 9
8.The Earth revolves around the Sun at a speed of about 18.5 miles/sec (30 km/sec)
9. there is no atmosphere on moon
10.If an atom were the size of a stadium, its electrons would be as small as bees
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What would happen if you drilled a tunnel through the center of the Earth and jumped into it?

What would happen if you drilled a tunnel through the center of the Earth and jumped into it..?

Want to really get away from it all? The farthest you can travel from home (and still remain on Earth) is about 7,900 miles (12,700 kilometers) straight down, but you'll have to journey the long way round to get there: 12,450 miles (20,036 kilometers) over land and sea.

Why not take a shortcut, straight down? You can get there in about 42 minutes -- that's short enough for a long lunch, assuming you can avoid Mole Men, prehistoric reptiles and underworld denizens en route. Granted, most Americans would end up in the Indian Ocean, but Chileans could dine out on authentic Chinese, and Kiwis could tuck into Spanish tapas for tea [sources: NOVA; Shegelski].

Of course, you'd be in for a rough ride. First, you'd have to pass through 22-44 miles (35-70 kilometers) of continental crust (3-6 miles/5-10 kilometers on the ocean floor) followed by 1,800 miles (2,900 kilometers) of mantle. After that, you'd have to traverse a Mars-sized outer core of liquid iron churning as hot as the sun's surface (10,000 degrees F, or 5,500 degrees C), then a solid, moon-sized inner core, and, some studies suggest, a liquid innermost core [sources: Angier; Locke; NOVA].

For sake of argument (and survival) let's pretend the Earth is a cold, uniform, inert ball of rock. While we're at it, let's ignore air resistance.

At the Earth's surface, gravity pulls on us at 32 feet (9.8 meters) per second squared. That means that, for each second you fall, you speed up by 32 feet per second -- but only near Earth's surface. Gravity is a function of mass, and mass is a property of matter. On the surface, all of Earth's matter lies below your feet but, as you fall, more and more of it surrounds you, exerting its own gravity. These horizontal tugs counterbalance each other and cancel out, but the increasing proportion of mass above your head exerts a growing counterforce to the proportionately decreasing mass below, so your acceleration slows as you near the core. At the planet's center, your acceleration due to gravity is zero -- Earth's mass surrounds you, gravity cancels out and you are weightless [sources: Locke; Singh].

You're still moving at a heck of a clip, though, so don't expect to stop there. Halfway to the center, your speed hits 15,000 mph (24,000 kph); 21 minutes after jumping in, you blow past the center at 18,000 mph (29,000 kph). Another 21 minutes later, with gravity slowing you as you go, you reach the far side and stop briefly in midair. Unless someone catches you, you'll then head back the way you came and start all over again. In our idealized case, this will continue indefinitely, like a pendulum or a spring, in a process called harmonic motion

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How compass apps can tell direction..??

 How compass apps can tell direction..??

If you were to go back in history and meet with the explorers and navigators of yesteryear, they would probably be wielding — at least one — magnetic compass. Whip out your compass app on your smartphone, and they’d probably be flabbergasted — well, with that and your time machine. But how has the compass worked to help everyone from ancient Chinese seafarers to today’s Boy Scouts of America? And how exactly does that timeworn technology work in your iPhone?

First, we’ll go over the magnetic compass. This trustworthy piece of equipment has been around since 200 BCE, according to William Lowrie, a professor emeritus at ETH Zurich. Navigators started using this compass regularly on land and sea closer to 1000 CE, in present-day China. The standard magnetic compass of the 20th century is made up of a magnetized needle in its heart with a face showing cardinal directions — north, south, east, and west. The needle is mounted on a surface with low friction so that it can easily turn; if held flat, one end of the needle will point toward magnetic north and one to magnetic south.

The compass is able to determine north and south due to the magnet’s interaction with the Earth’s magnetic field. The cause of the magnetic field is not completely known, but geologists have made hypotheses regarding the phenomenon by analyzing the layers of the Earth. The Earth is made up of an outer crust, followed by the upper mantle, the inner mantle, the outer core, and then finally the inner core at the very center. The inner core is made up mostly of molten iron, but the very center of the inner core is under so much pressure that the iron becomes solid, according to howstuffworks.com. It is believed that the rotation of the Earth and the immense heat from the core cause the iron to move in a rotational pattern. This rotational pattern may be the source of the magnetic field that we see on Earth. The field produced is very weak, however, which is why the needle on the compass needs to be very lightweight and on a surface with minimal friction.

As expected with any technology created over two millenniums ago, the compass has its issues. First, it has to be completely level to work — making it rather difficult to use on something like an airplane. Also, a magnetic compass can take a long time to correct itself. Another confusing thing is that the magnetic north pole is actually the geographical south pole (and vice-versa).

So if the traditional needle compass works because of a small magnet, how do the compass apps in phones work? As it turns out, the smartphones do have a small magnetometer, which can measure the Earth’s magnetic field. This information is combined with an accelerator inside the phone. The accelerator gets information regarding the phone’s position in space. It is able to pinpoint the phone’s position from solid-state sensors within the phone that can measure their tilt and movement. The information provided by these devices means that the compass app can display cardinal directions no matter which orientation the phone is in, according to the algorithmic software development company Sensor Platforms.

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Some Amazing Facts Collection

*********{Some Amazing Facts Collection}**********

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1.If an atom were the size of a stadium, its electrons would be as small as bees

2.Laser is an abbreviation of Light Amplification by Stimulated Emission of Radiation.

3.At 25, Physicist Lawrence Bragg is the youngest person to receive a Nobel Prize.

4.The effect of Relativity made Astronaut Sergei Avdeyev a fraction of a second younger upon his return to Earth after 747 days in space.

5.The amount of water beneath our ground soil is 50 times as much as all the water in the rivers and lakes combined.

6.The world's densest wood, the Black Ironwood (Olea laurifolia), does not float on water and therefore sinks

7.Due to the effect of Thermal Expansion, the Eiffel Tower is upto 15 cm taller in summer

8.After helium and hydrogen, the most common element on the Sun is oxygen

9.Boomerang Nebula is the coldest known place in the universe

10.The Moon is moving away from the Earth 3.8 cm every year.

 
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Geometric Optics

1 Real images are always inverted.
2 Virtual images are always upright.
3 Diverging lens (concave) produce only small virtual images.
4 Light rays bend away from the normal as they gain speed and a longer wavelength by entering a slower (n) medium {frequency remains constant}.
5 The focal length of a converging lens (convex) is shorter with a higher (n) value lens or if blue light replaces red.

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Facts

         

           Mechanics

1. Weight (force of gravity) decreases as you move away from the earth by distance squared.
2. Mass and inertia are the same thing.
3. Constant velocity and zero velocity means the net force is zero and acceleration is zero.
4. Weight (in newtons) is mass x acceleration (w = mg). Mass is not weight!
5. Velocity, displacement [s], momentum, force and acceleration are vectors.
6. Speed, distance [d], time, and energy (joules) are scalar quantities.
7. The slope of the velocity-time graph is acceleration.
8. At zero (0) degrees two vectors have a resultant equal to their sum. At 180 degrees two vectors have a resultant equal to their difference. From the difference to the sum is the total range of possible resultants.
9. Centripetal force and centripetal acceleration vectors are toward the center of the circle- while the velocity vector is tangent to the circle.
10. An unbalanced force (object not in equilibrium) must produce acceleration.
11. The slope of the distance-tine graph is velocity.
12. The equilibrant force is equal in magnitude but opposite in direction to the resultant vector.
13. Momentum is conserved in all collision systems.
14. Magnitude is a term use to state how large a vector quantity is.

Energy

1. Mechanical energy is the sum of the potential and kinetic energy.
2. Units: a = [m/sec²], F = [kg•m/sec²] (newton), work = pe= ke = [kg•m²/sec²] (joule)
3. An ev is an energy unit equal to 1.6 x 10^-19 joules
4. Gravitational potential energy increases as height increases.
5. Kinetic energy changes only if velocity changes.
6. Mechanical energy (pe + ke) does not change for a free falling mass or a swinging pendulum. (when ignoring air friction)
7. The units for power are [joules/sec] or the rate of change of energy.

Electricity

1. A coulomb is charge, an amp is current [coulomb/sec] and a volt is potential difference [joule/coulomb].
2. Short fat cold wires make the best conductors.
3. Electrons and protons have equal amounts of charge (1.6 x 10^-19 coulombs each).
4. Adding a resistor in parallel decreases the total resistance of a circuit.
5. Adding a resistor in series increases the total resistance of a circuit.
6. All resistors in series have equal current (I).
7. All resistors in parallel have equal voltage (V).
8. If two charged spheres touch each other add the charges and divide by two to find the final charge on each sphere.
9. Insulators contain no free electrons.
10. Ionized gases conduct electric current using positive ions, negative ions and electrons.
11. Electric fields all point in the direction of the force on a positive test charge.
12. Electric fields between two parallel plates are uniform in strength except at the edges.
13. Millikan determined the charge on a single electron using his famous oil-drop experiment.
14. All charge changes result from the movement of electrons not protons (an object becomes positive by losing electrons)

Magnetism

1. The direction of a magnetic field is defined by the direction a compass needle points.
2. Magnetic fields point from the north to the south outside the magnet and south to north inside the magnet.
3. Magnetic flux is measured in webers.
4. Left hands are for negative charges and right hands are for positive charges.
5. The first hand rule deals with the B-field around a current bearing wire, the third hand rule looks at the force on charges moving in a B-field, and the second hand rule is redundant.
6. Solenoids are stronger with more current or more wire turns or adding a soft iron core.

Wave Phenomena

1. Sound waves are longitudinal and mechanical.
2. Light slows down, bends toward the normal and has a shorter wavelength when it enters a higher (n) value medium.
3. All angles in wave theory problems are measured to the normal.
4. Blue light has more energy. A shorter wavelength and a higher frequency than red light (remember- ROYGBIV).
5. The electromagnetic spectrum (radio, infrared, visible. Ultraviolet x-ray and gamma) are listed lowest energy to highest.
6. A prism produces a rainbow from white light by dispersion (red bends the least because it slows the least).
7. Light wave are transverse (they can be polarized).
8. The speed of all types of electromagnetic waves is 3.0 x 10⁸ m/sec in a vacuum.
9. The amplitude of a sound wave determines its energy.
10. Constructive interference occurs when two waves are zero (0) degrees out of phase or a whole number of wavelengths (360 degrees.) out of phase.
11. At the critical angle a wave will be refracted to 90 degrees.
12. According to the Doppler effect a wave source moving toward you will generate waves with a shorter wavelength and higher frequency.
13. Double slit diffraction works because of diffraction and interference.
14. Single slit diffraction produces a much wider central maximum than double slit.
15. Diffuse reflection occurs from dull surfaces while regular reflection occurs from mirror type surfaces.
16. As the frequency of a wave increases its energy increases and its wavelength decreases.
17. Transverse wave particles vibrate back and forth perpendicular to the wave direction.
18. Wave behavior is proven by diffraction, interference and the polarization of light.
19. Shorter waves with higher frequencies have shorter periods.
20. Radiowaves are electromagnetic and travel at the speed of light (c).
21. Monochromatic light has one frequency.
22. Coherent light waves are all in phase.

Geometric Optics

1. Real images are always inverted.
2. Virtual images are always upright.
3. Diverging lens (concave) produce only small virtual images.
4. Light rays bend away from the normal as they gain speed and a longer wavelength by entering a slower (n) medium {frequency remains constant}.
5. The focal length of a converging lens (convex) is shorter with a higher (n) value lens or if blue light replaces red.

Modern Physics

1. The particle behavior of light is proven by the photoelectric effect.
2. A photon is a particle of light {wave packet}.
3. Large objects have very short wavelengths when moving and thus can not be observed behaving as a wave. (DeBroglie Waves)
4. All electromagnetic waves originate from accelerating charged particles.
5. The frequency of a light wave determines its energy (E = hf).
6. The lowest energy state of a atom is called the ground state.
7. Increasing light frequency increases the kinetic energy of the emitted photo-electrons.
8. As the threshold frequency increase for a photo-cell (photo emissive material) the work function also increases.
9. Increasing light intensity increases the number of emitted photo-electrons but not their KE.


Internal Energy


10. Internal energy is the sum of temperature (ke) and phase (pe) conditions.
11. Steam and liquid water molecules at 100 degrees have equal kinetic energies.
12. Degrees Kelvin (absolute temp.) Is equal to zero (0) degrees Celsius.
13. Temperature measures the average kinetic energy of the molecules.
14. Phase changes are due to potential energy changes.
15. Internal energy always flows from an object at higher temperature to one of lower temperature.

Nuclear Physics

1. Alpha particles are the same as helium nuclei and have the symbol
2. The atomic number is equal to the number of protons (2 for alpha)
3. Deuterium  is an isotope of hydrogen
4. The number of nucleons is equal to protons + neutrons (4 for alpha)
5. Only charged particles can be accelerated in a particle accelerator such as a cyclotron or Van Der Graaf generator.
6. Natural radiation is alpha , beta and gamma (high energy x-rays)
7. A loss of a beta particle results in an increase in atomic number.
8. All nuclei weigh less than their parts. This mass defect is converted into binding energy. (E=mc²)
9. Isotopes have different neutron numbers and atomic masses but the same number of protons (atomic numbers).
10. Geiger counters, photographic plates, cloud and bubble chambers are all used to detect or observe radiation.
11. Rutherford discovered the positive nucleus using his famous gold-foil experiment.
12. Fusion requires that hydrogen be combined to make helium.
13. Fission requires that a neutron causes uranium to be split into middle size atoms and produce extra neutrons.
14. Radioactive half-lives can not be changed by heat or pressure.
15. One AMU of mass is equal to 931 meV of energy (E = mc²).
16. Nuclear forces are strong and short ranged.

DO YOU KNOW ??

1)The Dead Sea is so dense with salt, you can easily float on it without drowning
 
2)The world's densest wood, the Black Ironwood (Olea laurifolia), does not float on water and therefore sinks.

3.The mass of our entire atmosphere is estimated to be some 5.5 quadrillion tons (55 followed by 14 zeros).

4.Chewing gum was invented by a dentist, named William Semple - as a way to exercise your jaws.

5 The diameter of a proton is approximately 0.000000000001 mm (1/25,000,000,000,000 inch).

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