AccessScience: McGraw-Hill Encyclopedia of Science & Technology Online

Unit 2. Electricity and Magnetism
V. Electromagnetism

1.Which of the following can be used directly to measure the EMF induced in a loop of wire?
ammeter
voltmeter
ohmmeter
nanometer
Wheatstone Bridge
2.A loop of wire, shown in the diagram above, is situated in a constant magnetic field B which points in the -z direction. This magnetic field extends throughout the region of interest. The x, y, and z axes are drawn on the diagram. Which of the following procedures would induce a current in the loop?
Moving the loop along the x axis
Moving the loop along the y axis
Moving the loop along the z axis
Rotating the loop about the x axis
Rotating the loop about the z axis
3.The magnetic field inside a solenoid with n turns per unit length changes at a constant rate, inducing a current I in the solenoid. If the total number of turns N is doubled, keeping n constant, what is the new current in the solenoid?
(1/4)I
(1/2)I
I
2I
4I
4.The RL circuit shown above has been connected to a battery for along time. At time t = 0, the switch is thrown from position 1 to position 2. Which of the following graphs best represents the voltage V across the resistor as a function of time?


A
B
C
D
5.Which of the following is the unit of inductance?
volt per meter
tesla
weber
henry
farad
Questions 6 and 7 refer to the image below
In the LC circuit shown above, the capacitor of capacitance C initially carries charge Q. The inductor has inductance L. The switch is closed at time t = 0.

6.Which of the following graphs represents the potential difference V across the inductor as a function of time?



A
B
C
D
7.Now the charge initially stored on the capacitor is doubled. How will this change affect the maximum energy stored on the inductor?
It will not change.
It will double.
It will be half as much.
It will quadruple.
It will be one fourth as much.
8.The rectangular wire loop of resistance R shown above enters the magnetic field B moving at speed v. What is the magnitude and direction of the induced current in the loop just as it enters the field?
Zero current is induced.
Bvb/R, clockwise
Bva/R, clockwise
Bvb/R, counterclockwise
Bva/R, counterclockwise
9.In which of the following geometries could Maxwell's displacement current be appended to Ampere's Law to give a complete description of the relationship between current and magnetic field?
The region between the poles of two bar magnets
A rectangular current-carrying circuit of wire including a parallel-plate capacitor
A rectangular current-carrying circuit of wire including a resistor
A rectangular current-carrying circuit of wire including an inductor
A circular current-carrying circuit of wire including a resistor
10.The magnetic field B through the rectangular wire shown above points into the page. Its magnitude is given as a function of time by , where k is a positive constant. Which of the following is correct about the induced current in the rectangular wire?
It is clockwise and increasing.
It is counterclockwise and constant.
It is clockwise and constant.
It is counterclockwise and decreasing.
It is clockwise and decreasing.