Question

1. (a) Which part of an atom is positively charged, and which part is negatively charged? (b) How does the charge of an electron compare with the charge of another electron? (c) How does the charge of an electron compare with the charge of a proton?

2. Can charge be created or destroyed? How does that answer relate to the conservation of charge?

3. How is electric charge similar to mass? How are they different?

4. What are two ways electric charge can be transferred?

5. Describe what a conducting object wants in terms of charge distribution and interior electric field?

6. What happens to an insulator in the presence of a charged object?

7. It is said that a gravitational field, unlike an electric field, cannot be shielded. But the gravitational field at the center of Earth cancels to zero. Isn’t this evidence that a gravitational field can be shielded?

8. (a) If an electron at a certain distance from a charged particle is attracted with a certain force, how will the force compare at twice this distance? (b) Is the charged particle in this case positive or negative?

9. How is Coulomb’s law similar to Newton’s law of gravitation? How is it different?

10. What is the significance of the fact that G in Newton’s law of gravitation is a small number and k in Coulomb’s law is a large number when both are expressed in SI units?

11. In terms of net charge, how does an electrically polarized object differ from an electrically charged object?

12. Give two examples of common force fields?

13. How are the magnitude and direction of an electric field determined with electric field lines?

14. Give the sign of the charges and the relative (stronger or weaker) field strength of both particles for each of the four drawings below.

15. What is the main difference between DC and AC?

16. What factors might affect the resistance of a wire?

17. To make a makeshift heater, you want to put a voltage across a metal rod and make it heat up. Which type of material should you use in this situation: a super-conducting material or a semi-conducting material? Why?

18. How much current is drawn by a lamp that has a resistance of 100 ohms when a voltage of 50 volts is impressed across it?

19. If the resistance of your body were 100,000 ohms, what would be the current in your body when you touched the terminals of a 12-volt battery?

20. If your skin were very moist, so that your resistance was only 1000 ohms, and you touched the terminals of a 24-volt battery, how much current would you draw?

21. What is the source of electrons in a circuit?

22. What happens to the light intensity of each lamp in a series circuit when more lamps are added to the circuit?

23. A 9-V battery is in series with three bulbs. (a) If the current through one of the bulbs is 1 A, what is the current through each of the other two bulbs? (b) If the voltage across bulb 1 is 2 V, and across bulb 2 is 4 V, what is the voltage across bulb 3?

24. What happens to the current in other lamps if one lamp in a series circuit burns out?

25. A toaster (570 Ω), a television (2500 Ω), and a printer (9700 Ω) are hooked up in series to the same circuit in a household electrical system. What is their combined resistance through this circuit?

26. What happens to the light intensity of each lamp in a parallel circuit when more lamps are added in parallel to the circuit?

27. What happens if one device in a parallel circuit fails?

28. A toaster (570 Ω), a television (2500 Ω), and a printer (9700 Ω) are hooked up in parallel to the same circuit in a household electrical system. What is their combined resistance through this circuit?

29. In the circuit shown below, (a) what is the current in amperes through the pair of 10-ohm resistors? (b) through each of the 8-ohm resistors?

30. Find the equivalent resistance of the circuit shown below.

31. Will a 1200-watt hair dryer operate on a 120-volt line if the current is limited to 15 amperes by a safety fuse? Why or why not?

32. How can you prevent overloading in circuits?

33. (a) How much power is used by a calculator that operates on 8 volts and 0.1 ampere? (b) If it is used for one hour, how much energy does it use?

34. Give an expression for electric power in terms of (a) current and voltage; (b) current and resistance; (c) voltage and resistance.

35. Does every magnet have to have a north and a south pole?

36. Iron filings sprinkled on paper that covers a magnet were not initially magnetized. Why, then, do they line up with the magnetic field of the magnet?

37. What makes a magnetic compass point northward?

38. On an atomic scale, what is the source for magnetism in permanent magnets?

39. What is the direction of the magnetic field outside of a magnet?

40. Describe the shape of magnetic field lines in a current-carrying wire that is (a) straight. (b) formed into a loop.

Answer 1

a) Atom has two parts (i) Nudels (11) Orbiting Electron The orbiting Flectrons are negatively charged and Nucleus is positively charged. b) Charge of two different electron are ze. -1-602x10-19 same of a C)0 Charge proton is +1.602 x 10-19 € So, proton's charge is same but opposite in magnitude of electron. (*) NO leharge cannot be created or destroyed Total charge is conserved. For an the Universe isolated system charge cannot be destroyed or created. So total charge of the system remain conserved. Similarly, we can an isolated system. Hence in Universe charge is conserved assume 09