A magnet is moved in and out of a coil wired to a voltmeter. Which statement about the induced voltage is correct?
So far, the magnet has done all the moving. Here is the opposite arrangement: a horseshoe magnet rests on a bench, and a straight wire hangs in the space between its poles. A meter is wired across the wire's ends.
Three trials answer one question. When is an EMF induced across the wire?
The wire is swept across the field between the poles. While the wire moves, an EMF is induced across it.
The wire stops between the poles. The EMF drops to zero.
Now the wire is held still, and the magnet is pulled away instead. While the magnet moves, an EMF is induced again.
Moving the wire and moving the magnet both count as relative motion: one moving past the other.
A straight wire is swept between the poles of a magnet. Is an EMF induced across the wire?
A wire and a magnet rest side by side. Is an EMF induced across the wire?
A metal rod is swept between the poles of a magnet, then held still. When is an EMF induced across the rod?
An EMF is induced while there is relative motion between the conductor and the field.
The rod moves only during the sweep.
An EMF is induced across the rod only while it is being swept. Once the rod is held still, the EMF is zero.
A wire is held still while the magnet beneath it is slid away. Is an EMF induced across the wire?
Moving the magnet and moving the wire both count as relative motion.
The magnet is moving past the wire.
Yes. An EMF is induced across the wire while the magnet slides away.
A coil is lifted off a resting magnet. Is an EMF induced in the coil?
A wire is swept downward between the poles of a magnet. Which statement is correct?
First a coil is pulled sideways off a resting magnet. Then the coil is held still while the magnet is pulled away. In which cases is an EMF induced?
A wire is being swept between a magnet's poles, and a voltmeter shows a reading. Which change makes the reading drop to zero?