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Physics109 Quiz5 April4,2014

1. Why do clothes often cling together after tumbling in a clothes dryer? (A) There is less water in the clothes (B) Electrons get rubbed off some items onto others (C) Protons get rubbed off some items onto others (D) The resistance to flow of increases as the clothes dry

2. If an electron and a proton both experience the same electric , (A) the proton will have greater acceleration. (B) the electron will have greater acceleration. (C) their accelerations will have the same magnitude. (D) neither will accelerate.

3. ’s law says the force between two charged points is (A) proportional to the charges (B) inversely proportional to the distance between the points squared (C) related by the proportionality constant 8.988 x 109 N m2/C2 (D) A, B and C

4. Who originally named electric charges as positive and negative? (A) Andre Marie (B) Michael (C) (D) Charles Augustin de Coulomb

5. A positive point charge is placed at a point in space that has an electric field pointing due north. What direction will the point charge move. (A) due north (B) due south (C) due east (D) due west

6. Good electrical conductors are usually good thermal conductors because (A) neither type of object has a high specific heat. (B) both types of objects have low density. (C) of pure coincidence. (D) electrons are responsible for thermal and electric conduction. 7. In the dark, the photo-conductors used in most xerographic copiers are (A) super-conductors. (B) insulators. (C) semi-conductors. (D) conductors.

8. A 12 battery is connected across a 36Ω resistor. The current through the resistor is: (A) 3 (B) 0.3 Amperes (C) 0.33 Ampere (D) 0.033 Ampere

9. An electrical appliance has a power rating of 600 when connected to a 120 volt electrical outlet. What is the resistance of the appliance? (A) 24 Ω (B) 12 Ω (C) 5 Ω (D) 0.48 Ω

10. You are working with a and it breaks in half. You then end up with (A) Two north poles only (B) Two , each with a south and a north pole. (C) One north and one south pole (D) Two south poles only

11. Electricity and are different because (A) Electrical decrease with increasing separation. (B) Only magnetism has to do with electrons. (C) There are no electric monopoles. (D) There are no magnetic monopoles.

12. The source of all magnetism is (A) ferromagnetic materials (B) tiny domains of aligned atoms (C) tiny pieces of iron (D) moving electric charges 13. A magnetic field points due south and parallel to the surface of the earth. A positive charge is moving due east parallel to the earth’s surface. What is the direction of the magnetic force on the positive charge (A) up (B) down (C) south (D) north

14. A straight wire with a length of 0.2 meter has a current of 10 amperes flowing through it in a region where there is a magnetic field of 2 . The field is perpendicular to the wire. The magnitude of the force on the wire is: (A) 0.2 Newtons (B) 0.4 Newtons (C) 2 Newtons (D) 4 Newtons

15. Faraday’s law says (A) current times resistance is equal to (B) a changing magnetic field produces an induced voltage (C) there are no magnetic mono-poles (D) a changing electric field produces an induced magnetic field

16. An electrical generator (A) is normally used to create DC power (B) generates electrical current by rotating a coil in an magnetic field (C) use a magnetic field created by magnetic mono-poles (D) can not make AC power

17. The principal advantage of sending across country on very high voltage transmission lines is that (A) they carry less energy per charge than low voltage transmission lines. (B) electric power lost in the wires is greatly reduced. (C) these transmission lines are less likely to get in the way than low voltage transmis- sion lineswhich are much closer to the ground. (D) they carry much more current than low voltage transmission lines.

18. James showed (A) a changing magnetic field produces an (B) is an electromagnetic wave (C) momentum is based on translational symmetry (D) that magnetic mono-poles could not exist