Induced Voltage and Inductance

A uniform 4.5 T magnetic field passes perpendicularly through the plane of wire loop 0.10 m² in area. What flux passes through the loop?

• 5.00 Tm²

• 0.450 Tm²

• 0.250 Tm²

• 0.135 Tm²

A coil in a magnetic field encloses a flux of 0.256 Tm² when the angle between the normal to the coil and the direction of the magnetic field is 70.0°. What flux would go through the coil if the angle were changed to 40.0°?

• 0.332 T·m²

• 0.198 T·m²

• 0.114 T·m²

• 0.573 T·m²

A sensitive ammeter is connected to a wire loop and placed within the magnetic field of a strong horseshoe magnet. The ammeter shows a deflection when:

• the wire is moved parallel to the field.

• the wire is moved perpendicularly to the field.

• neither wire nor magnet is moving.

• the wire's axis is parallel to the field.

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) is:

• clockwise.

• counterclockwise.

• zero.

• along the length of the magnet.

An airplane with a wingspan of 60.0 m flies parallel to the Earth’s surface at a point where the downward component of the Earth's magnetic field is 0.400 x l0^-4 T. If the induced potential between wingtips is 0.900 V, what is the plane’s speed?

• 250 m/s

• 338 m/s

• 375 m/s

• 417 m/s

A straight wire of length is oriented east-west and is in a magnetic field B pointing north. The wire is moving downward at a constant speed v. Which end of the rod is positively charged?

• neither

• the east end

• the west end

• both ends

A bar magnet is held above the center of a conducting ring in the horizontal plane. The magnet is dropped so it falls lengthwise toward the center of the ring. Will the falling magnet be attracted toward the ring or be repelled by the ring due to the magnetic interaction of the magnet and the ring?

• It will be attracted.

• It will be repelled.

• It will be attracted only if the north end of the magnet is the leading end as it falls toward the ring.

• It will be attracted only if the south end of the magnet is the leading end as it falls toward the ring.

A 0.200-m wire is moved parallel to a 0.500-T magnetic field at a speed of 1.50 m/s. What emf is induced across the ends of the wire?

• 2.25 V

• 1.00 V

• 0.600 V

• zero

A metal rod is falling toward the surface of the Earth near the equator. As it falls, one end of the rod becomes positively charged due to the motional emf of the rod through the Earth's magnetic field. The rod is oriented so that:

• the rod is vertical with the positive end higher.

• the rod is horizontal with the positive end toward the north.

• the rod is horizontal with the positive end toward the east.

• the rod is horizontal with the positive end toward the west.

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?

• enhance the effect which produces it

• produce a greater heating effect

• produce the greatest voltage

• oppose the effect which produces it