1. ICS Physics End of Physics Review 9-12 Science Std: Phys 3, 4, 5

2. Topic: The Right Tool You must choose the right equipment to get the best scientific readings To record sounds you would use a To measure electrical charge, current or voltage you would use a To measure temperature you would use a To measure earthquake energy you would use a Std I&E 1a microphone seismograph Electrometer, ammeter or Voltmeter thermometer

3. Topic: The Right Tool Once you have your readings, you need to organize and compare your readings You can start by putting the data into a And once you put it into the spreadsheet, you can look at the data on a You can take the data from the table and put it in a Std I&E 1a table spreadsheet graph

4. Topic: Entropy* Entropy is a physics term that describes: The amount of disorder is in a system High Entropy means something is disorganized, messy and everything is behaving badly It is a fact that Entropy is always increasing Low Entropy means something is very organized, clean and everything is behaving nicely Std 3f And things will move to a less orderly state

5. Topic: Wave Types Waves have 2 different shapes The first type is a transverse wave We made transverse waves when we were shaking a slinky The second type is a longitudinal wave EM Waves are transverse waves Std 4b Sound waves are longitudinal waves

6. Topic: Wave Motion As a wave moves through something it makes parts of the material move As a transverse wave moves by: If you were on a surf board on the ocean The transverse wave would make you move up and down It makes the material (or anything that is on it) move up and down Std 4a Watch the little black dot as the transverse wave goes past it

7. Topic: Sound Waves Sound waves are longitudinal waves Sound waves need a material (medium) to travel through When the molecules bump into each other, they transfer the wave energy from one molecule to the next in a direction parallel to the direction of the sound Sound waves move through the medium by having molecules bump into each other Std 4b

8. Topic: Speed of Sound Several things affect the speed of sound in materials Temperature: Higher temperature = sound moves faster Flexibility: Lower flexibility = sound moves faster Density: Higher density = sound moves faster Std 4d Sound moves faster in the desert heat than the artic cold Sound moves faster in water or steel than in air Sound moves faster in a stiff plastic pole than a soft plastic toy

9. Topic: EM Wave Spectrum Electromagnetic Waves are a special kind of wave Depending on the frequency (and the wavelength) of the wave, we have special names for the waves All of these waves are transverse waves and can move without going through a material (medium) Some of the special names are radio waves, microwaves, ultraviolet waves, x-rays and visible light Std 4e

10. Topic: EM Wave Speed Electromagnetic waves are special for many reasons They travel faster than anything else known today They go at the speed of light And the speed of light is: 3 x 10 8 meters per second In a vacuum (out in space) they all travel at the same speed Std 4e

11. Topic: Refraction Refraction is a bending of waves caused by a change in the speed of the wave This can be caused by either: Or a change in the material that causes a change in the speed of the wave Going from one material into another material with a different wave speed Std 4f

12. Topic: Index of Refraction You can measure how much a wave will bend using the Index of Refraction (n) The Index of Refraction is a measure of how much the velocity changes in a medium The bigger the Index of Refraction, the slower the wave speed in the material For light, the Index of Refraction is the speed of light in a vacuum (c) divided by the speed of light in the material (v) Std 4e

13. Topic: Index of Refraction If you compare the Index of Refraction for 2 materials… You can tell how much the wave is going to bend If the indices of refraction are not similar (numbers are far apart) the wave will bend a lot If the indices of refraction are similar (numbers are close to each other) the wave will bend a little Std 4f

14. Topic: Doppler Effect The Doppler Effect is an apparent change in the frequency of a wave The change is caused by relative motion between the source and the observer If the sound is going away from the listener, the pitch goes down If the sound is not getting closer or farther away from the listener, the pitch doesn’t change If a sound wave is coming towards the listener, the pitch goes up Std 4f The bigger the difference in speed between the sound and the listener, the bigger the change in pitch

15. Topic: Sound Beats When sound waves add together it is called interference If two sound frequencies are close together, when they add you hear sound beats The smaller the difference, the smaller the beat frequency The larger the difference, the larger the beat frequency The number of beats you hear depends on the difference in the sound frequencies Std 4f If there is no difference, you don’t hear any beats

16. Topic: Sound Limits We know that sound is a longitudinal wave And that all waves (except for EM waves) need to travel through something (a medium) If you don’t have a medium, sound waves can’t travel That is why sound won’t travel in a vacuum (in a place without any air) So sound waves need a medium to travel through (air, water, etc.) Std 4f And in space, no one can hear you scream……

17. Topic: Wave Energy All waves transfer energy when they move Some waves need a medium to move, some don’t We saw this when we did the lab with the string telephones If a wave needs a medium, the medium ends up in the same place where it started after the wave goes past Std 4a The sound waves moved through the string but it didn’t move the string

18. Topic: Wave Energy So what happens to this energy? Sound waves can cause things to move When they rub against each other, friction causes them to heat up So if you had a loud enough sound wave, you could heat up water! And when things move they rub against each other Std 4d

19. Topic: Electrostatic Force Electrically charged particles can be either positive (+) or negative (-) Charged particles can push or pull on each other (force) The amount of charge (+) or (-) – more charge = more force The distance between the charges – more distance = less force The amount of force depends on 2 things: Std 5e If the distance gets big enough, the force goes to 0 (goes away)

20. Topic: Electrostatic Force When you have 2 charges, they can either pull or push on each other If the charges are the same (alike) they push against each other So remember that opposites attract and alike repel If the charges are opposite (different) they pull towards each other Std 5e

21. Topic: Electrostatic Force When we draw Electrostatic Forces, we show the amount of force a special way If we draw a small number of lines we have a small force If we draw many lines we have a big force So more lines = more force If we draw more lines we have a bigger force Std 5m And the closer the lines are to each other = the stronger the force is

22. Topic: Electrostatic Force How much does the force change? This is the equation for the amount of force between charges The amount of charge = q The distance between the charges = r Std 5e 2x the charge = 2x the force 3x the charge = 3x the force 2x the distance = 1/4x the force 3x the distance = 1/9x the force A change in the distance between the charges has more affect because the distance is squared in this equation

23. Topic: Right Hand Rule When an electric current goes through a wire It makes a magnetic field around the wire Wrap your right hand around the wire Point your thumb in the direction of the current The direction of the field depends on the Right Hand Rule Std 5h Your fingers wrap in the direction of the magnetic field You can see this if you put a compass next to the wire

24. Topic: Magnetic Induction When you move a magnet next to a wire… The magnet will induce (or make) a voltage in the wire So if you move a magnet next to wires in an electric circuit, you will cause electric current to flow When you have a voltage in a wire that is part of a electric circuit… Std 5h Electric current will flow through the circuit

25. Topic: Transistors When transistors were invented in the 1940’s They made many changes in electronics They could be made cheaper They could be made smaller And they used less energy Std 5d With all these changes they quickly replaced bigger vacuum tubes

26. Topic: Transistors Transistors are designed to do 2 things…. The 1 st is to be a switch to turn on and off current The 2 nd is to add energy to a weak input signal The first function is used in a computer The second function is used in an amplifier Std 5d

27. Topic: Transistors Transistors have changed modern electronics because: They can amplify small inputs into larger output signals They don’t break easily like old vacuum tubes They are smaller than vacuum tubes So – the computers, radios and cell phones we use today are much smaller and tougher Std 5d

28. Topic: Plasma Plasma is the 4 th state of matter (solid, liquid, gas…) It happens when you take a gas and either heat it to a very hot temperature or put a large voltage on it A plasma is atoms of gas that have had their electrons pulled off so they are made of positive ions and free electrons Because they have ions and electrons they are good electric conductors You can find plasmas in the sun (very hot) or in a fluorescent light bulb (large voltage) Std 5i Plasma is like a gas, but a gas can’t conduct electricity