Induce Voltages and Inductance

According to Lenz’s law the direction of an induced current in a conductor will be that which tends to

produce which of the following effects?

• Reverse the change in magnetic flux
• Ignore the change in magnetic flux
• Enhance the change in magnetic flux
• Oppose the change in magnetic flux

A bar magnet is falling through a loop of wire with constant velocity. The south pole enters first. As

the magnet leaves the wire, the induced current (as viewed from above):

• Clockwise
• No current induced
• Alternating current
• Counterclockwise

A coil is placed in a changing magnetic field and an emf is induced. What happens to the induced emf

if the rate of change of magnetic field quadruples?

• The induced emf will quadruple.
• The induced emf will remain the same.
• The induced emf will decrease.
• The induced emf will become negative.

The basic function of the electric generator is which of the following conversion processes?

• Mechanical energy into electrical energy
• Chemical energy into mechanical energy
• Electrical energy to mechanical energy

• Potential energy into kinetic energy

Two loops of wire are arranged so that a changing current in one will induce a current in the other. If

the current in the first is increasing clockwise by 1.0 A every second, the induced current in the second

loop will:

• Alternating in both directions

• Remain constant counterclockwise

• Increasing

  clockwise

• Increasing Counterclockwise

The function of the electric motor is which one of the following conversion processes?

• Mechanical to electrical energy
• Chemical to mechanical energy
• Thermal to electrical energy
• Electrical to mechanical energy

What is the self-inductance in a coil that experiences a 3.0-V induced emf when the current is changing

at a rate of 110 A/s?

• 83 mH

• 45 mH

• 27 mH

• 15 mH

What is the stored energy in a 0.50-mH coil carrying a current of 4.0 A?

• 2 x 10^-3 J

• 8 x 10^-3 J

• 4 x 10^-3 J

• 1 x 10^-3 J

A loop of area 0.25 m² is in a uniform 0.02-T magnetic field.

If the flux through the loop is 3.83 x 10^-3 T·m²,

what angle does the normal to the plane of the loop make with the direction of the magnetic field?

• 90 degrees
• 40 degrees

• 45 degrees
• 30 degrees

• 125 mA

• 500 mA

• 900 mA

• 750 mA