1. What do the direction of forces between opposite charges look like? + -

The closer they get, the stronger the repulsive force. 2. When you move two nuclei closer together, what happens to the force of repulsion between them? The closer they get, the stronger the repulsive force.

3. Why do strands of hair move towards the comb after you comb your hair? The hair gave up electrons to the comb, so it has a positive charge, while the comb has a negative charge. Opposite charges attract.

4. When you bring two charged balloons closer to each other, what happens to the forces between them and what do they do? The closer the balloons get, the stronger the forces. Since the balloons have the same charge, they repel

5. Label the positive and negative charges in the picture. + -

6. Why are metals good conductors? They have loosely held electrons.

7. What causes an electric current? Movement of electrons.

8. What is an insulator? Some thing that resists the movement of electrons or heat.

9. How can you increase the current across a resistor? Increase the voltage or decrease the resistance.

10. If you have batteries in series, and one battery goes dead, what will happen to the current? The circuit is broken, so there is no current.

Nothing, each battery has a separate path. 11. If you have batteries in parallel, and one battery goes dead, what will happen to the current? Nothing, each battery has a separate path.

12. Label the circuits as series or parallel.

13. In a series circuit, what happens to the brightness if you add another lamp? The lamps get dimmer because the voltage is dived between the lamps.

14. In a parallel circuit, what happens to the brightness if you add another lamp? Nothing, each lamp has a separate path to the battery, so each has the same voltage.

15. In a series circuit, what happens if a lamp burns out? The circuit is broken, so all the lights go out.

16. In a parallel circuit, what happens if a lamp burns out? Only that light goes out.

17. What is true about the voltage in each branch of a parallel circuit? They are the same.

V=IR so I = V/R, R= 1/(1/2+1/4)=1.33 ohm 12 v / 1.33 ohm= 9 amps. 18. If you have a 2 ohm and a 4 ohm resistor in parallel with a 12 volt battery, what is the current in the circuit? V=IR so I = V/R, R= 1/(1/2+1/4)=1.33 ohm 12 v / 1.33 ohm= 9 amps.

V= IR so add the resistors together. V = 55 ohms times 1= 55 v 19. If you have a 10 ohm, 15 ohm and 30 ohm resistor in series, what voltage will produce a 1 amp current? V= IR so add the resistors together. V = 55 ohms times 1= 55 v

20. What device can increase or decrease voltage? A transformer can increase or decrease the voltage.

21. Where is a magnetic field the strongest? At the poles.

22. When two objects of different temperature are placed together, what happens to the internal energy of both? The warmer object transfers heat to the cooler object until both are at the same temperature.

23. What is the freezing point of water in Kelvin? Since Kelvin is oC plus 273, 0 oC is 273 Kelvin.

24. What is the boiling point of water in Kelvin? Since Kelvin is oC plus 273, 100 oC is 373 Kelvin.

25. If 100 grams of water at 40 oC is mixed with 100 grams of water at 20 oC what will be the final Temperature of the water? Since the mass of both water samples is the same, we can average the temperatures. 40 oC + 20 oC = 60 oC, 60 / 2 = 30 oC

26. Which solid has the highest specific heat ? A, since the temp changes the least with the addition of heat

27. Which way does heat flow? From hot to cold.

28. What do the laws of Thermodynamics tell us about energy and entropy? That the Universe tends to move towards more disorder (randomness)and less useful energy.

29. Which phase has the most entropy? Gas, since the molecules are spread randomly.

30. Which phase has the least entropy? Solid, since the molecules are arranged in a pattern.

31. How much heat has to be added to the substance to change it from a solid to a liquid? From 40kJ to 80kJ, so 40kJ added.

32. What does a wave carry? Energy, the matter only moves in circles.

33. What is the frequency of a wave with a velocity of 10 m/s and a wavelength of 2 meters? V = ג x f So f= v/ ג 10 m/s/2 m = 5/sec or 5 Hertz

34. What does amplitude measure in a wave? How much energy it carries.

35. A disturbance that only sends one wave is called a …. A pulse.

36. If you are 1000 meters from a noise, how long until you hear it 36. If you are 1000 meters from a noise, how long until you hear it? (use 340 m/s for speed of sound) V=d/t so t = d/t 1000m/ 340 m/s= 2.94 sec

37. Which part of the EM spectrum has the shortest wavelength? Gamma

38. Which part of the EM spectrum has the longest wavelength? Radio

Parallel to the direction of the energy. 39. As a longitudinal wave passes through a medium, how do the particles of the medium move? Parallel to the direction of the energy.

40. Circle the part of the graph that shows the loudest sound.

41. Put an x on the part of the graph that shows the quietest sound.

42. How does the speed of a radio wave compare to the speed of sound? Speed of light 300,000,000 m/s compared to speed of sound 340 m/s. Many times faster.

43. What does the angle of reflection equal? The angle of incidence.

44. What happens to the pitch of the sound from an object moving away from you? It gets lower since it takes longer for each wave to reach you.

45. What happens to the pitch of the sound from an object moving towards you? It gets higher since each wave gets to you faster than the one before.

46. What is it called when waves spread out after passing through a hole in a barrier? Difraction.

47. Light exhibits the properties of both….. Waves and particles.

48. Which color has the shortest wavelength? Violet

49. Which color has the longest wavelength? Red

50. A convex lens produces a (virtual/real) image. Lens that converges (brings together) light rays. Forms real images and virtual images depending on position of the object. In a real image the light rays intersect at the image location.

51. A concave lens produces a (virtual/real) image. Virtual, recall that a virtual image means no light rays reach the image location.

52. When electrons in an atom change levels, the atom emits…. A specific spectrum of color based on the energy level of the electron.

53. The photoelectric/ photoemissive effect means….. many metals emit electrons when light shines upon them. Electrons emitted in this manner may be called photoelectrons.

54. When the intensity of light increases, what happens to the number of photoelectrons that are emitted? The number increases.

55. How much energy is used by a 500 watt dryer that runs for 2½ hours? Energy is measured in Kilowatt hours (KwH). 500 watts times 2.5 hours= 1250 watt hrs. Divided by 1000 to change to Kwhr = 1.25 Kwhr

56. Inside the atom, what force holds the protons and neutrons together? The strong force.

57. Inside the atom, what force holds the electrons to the atom? The weak force.

58. Inside the atom, which is stronger, the strong force or the gravity between the particles? At the distances inside the atom, the strong force is stronger.