μ =
B
mgr
ext
Handle
μ
solenoid
1. A dipole μ(=IA) is rigidly attached to a sphere with a handle as shown in Figure 1. If the
magnetic torque and the gravitational torque balance one another then the magnetic moment is
(True, False)
Ta (out)
Ting (in)
Figure 1: Magnetic vector field Bert is not shown
left
upt in
e
down
ATO
out
Figure 2:
Mg
right
2. A 0.400 m long solenoid has 6720 turns of wire. A current of 14.5A flows in the solenoid.
(a) The strength of the magnetic field in the middle section of the solenoid is B
=
MonI
0.3067 [See Figure 2] (True, False)
(b) An electron inside the solenoid [in the middle section] travels perpendicular to the axis
of the solenoid with a speed of 6.50 x 105m/s [See Figure 2]. The magnetic force acting on the
electron is: F = quB sin 90 = qu(on I) sin 90 = 3.18 x 10-14 and it points up. (True, False)