# 1. What is the direction of the magnetic field from the

```1.
What is the direction of the magnetic field
from the left wire at the right wire?
A. Left
B. Right
C. Out of page
D. Into page
Correct answer is D (see Figure 20.7 b in the book)
2.
Which one or more of the following choices is (are) true.
A magnetic field:
1. can increase the speed of a moving particle. 2. can cause a moving particle to accelerate.
3. always exerts a force on a moving particle.
4. can exert a force on a moving particle
A. 2 and 3
B. 1 and 2
C. 2
D. 3
E. 2 and 4
The force, if any, is always perpendicular to the velocity, so the speed
does not change (1 is wrong). A perpendicular force causes an
acceleration (2 is right). If the velocity and the B-field are parallel, the
force is zero (3 is wrong). If the velocity and the B-field are not parallel,
the force is not zero (4 is right) &AElig; Correct answer is E
3.
A square current loop is placed in a uniform magnetic field
(see the drawing). The dashed line is the axis of rotation.
The magnetic field exerts
A.
C.
A net force and no torque
No net force and a torque
B. No net force and no torque
D. A net force and a torque
See figure 20.27(b) &AElig; correct answer is C
4.
Cutting a permanent magnet in two pieces....
A. Results always in separate North and South poles
B. Results sometime in separate North and South poles
C. Results in two magnets, each with North and South poles
Correct answer is C (see Figure 20.3)
5.
A 10 Ω resistor is connected to a 6 V battery. The power
dissipated in the resistor is
A. 360 W
B. 600 W
C. 60 W
D. 3.6 W
E. 0.06 W
P = I2R = IV = V2/R =(6 V)2/(10 Ω) = 3.6 W &AElig; correct answer is D
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