2. 1. ____The polarity of an electromagnet can be determined using the second right-hand rule. 2. ____Current passing through a conductor is increased from 10 A to 15 A. This decreases the strength of the magnetic field produced by the conductor. 3. ____The speed of an electric motor can be controlled by varying the amount of current through the motor. 4. ____Magnetic fields exit from the north poles of magnets and enter the south poles of magnets.

3. 5. ____Cathode ray tube computer monitors and TV screens use magnets to focus and direct particles on phosphor screens. 6. ____The electromotive force is a force that makes charges flow from a point of higher potential to lower potential. 7. ____Hans Christian Oersted discovered that a changing magnetic field produces an electric current. 8. ____A current is generated when a wire is moved parallel to a magnetic field. 9. ____Lenz’s law applies to both motors and generators. 10. ____In a step-down transformer, the current in the secondary circuit is less than the current in the primary circuit.

4.  There are four coils of wire being used as electromagnets. They all have the same size and are made up of the same material but have a different number of loops. Which coil will produce a magnetic field with the maximum strength when the same amount of current passes through all coils? a. a coil having 10 loops b. a coil having 30 loops c. a coil having 25 loops d. a coil having 45 loops

5.  Which rule is used to find the direction of force acting on a current-carrying wire in a magnetic field? a. the first right-hand rule b. the third right-hand rule c. the second right-hand rule d. the fourth right-hand rule

6.  A/An _____ is a magnet created when current flows though a wire coil. a. Solenoid b. electric motor c. Electromagnet d. armature

7.  The _____ is a method used to determine the direction of a magnetic field relative to the direction of conventional current. a. first right hand rule b. third right hand rule c. second right hand rule d. none of the above

8.  A uniform magnetic field of 0.25 T points vertically downward. A proton enters the field with a horizontal velocity of 4.0 10 m/s north. What are the magnitude and direction of the instantaneous force exerted on the proton as it enters the magnetic field? a. 1.6 10 -13 N west b. 1.6 10 -13 N downward c. 1.6 10 -13 N east d. 1.6 10 -13 N to the right

9.  Which rule is used to find the direction of force produced by electromagnetic induction? a. First right-hand rule b. Second right-hand rule c. Third right-hand rule d. Fourth right-hand rule

10.  A step-up transformer _____. a. increases voltage and current b. increases voltage and decreases current c. decreases voltage and increases current d. decreases voltage and current

11.  In an ideal transformer, the electric power delivered to the secondary circuit _____ the power supplied to the primary circuit. a. equals b. is greater than c. is less than d. is unrelated to

12.  Given a wire with a current in the direction towards you (out of the page), what can you say about the magnetic field produced by the wire? a. The magnetic field lines point away from the wire. b. The magnetic field lines point towards the wire. c. The magnetic field lines circle clockwise around the wire. d. The magnetic field lines circle counter-clockwise around the wire.

13.  Which one of these statements about electromagnetic induction is FALSE? a. Changing the magnetic field strength through a wire loop will induce a current. b. Moving a wire with no current through a constant magnetic field induces a current in the loop. c. Moving a magnetic field past a wire will induce a current d. A constant magnetic field will induce a current in a stationary wire.

14.  The two coils of a transformer MUST _____. a. be electrically insulated from each other b. be wound around the same iron cores c. have the same number of windings d. have the same resistance

15.  Transformers can change _____ with relatively little loss of energy. a. Magnetic fields b. Power c. Resistances d. Voltages

16.  A long coil of wire that contains many loops is called a(n) _____.  A group of neighboring atoms whose electrons’ magnetic fields all align in the same direction is called a(n) _____.  A(n) _______ is a device that converts electrical energy into rotational kinetic energy.  A(n) _______ is a device that converts rotational kinetic energy into electrical energy.