Back in the Circuits topic, you saw that a voltmeter reads the voltage between two points.
Here is a coil of wire with a voltmeter across its ends. There is no battery anywhere in the loop. So the meter should have nothing to read.
Now a bar magnet is about to slide into the coil. What will the meter show while the magnet moves?
A magnet slides into a coil. What does the coil's meter show while the magnet moves?
Here is the demonstration's whole record, kept as a table.
Where did that voltage come from? No battery made it, because the loop has none.
The moving magnet makes a voltage across the coil. We say the moving magnet induces a voltage.
The voltage exists only while the magnet is moving. While the magnet rests inside the coil, the reading is zero.
No battery is needed. The motion is what makes the voltage.
The magnet comes to rest inside the coil. What does the voltmeter show while it rests there?
A magnet rests inside a coil that has a voltmeter across its ends. The magnet is then lifted straight out. When does the meter show a reading?
A voltage is induced only while the magnet is moving.
The magnet moves only while it is being lifted out.
The meter shows a reading only while the magnet is being lifted out. Before the lift, and after it, the meter reads zero.
A magnet sits just outside a coil. It is pushed in, held still for two seconds, then pulled out. During which parts does the meter show a reading?
A voltage is induced only while the magnet is moving.
The magnet moves during the push in and during the pull out.
The magnet does not move during the two held seconds.
The meter shows a reading during the push in and during the pull out. It reads zero during the two held seconds.
Moving a magnet in a coil makes a voltage across the coil. What is this effect called?
Which action induces a voltage across a coil?
A magnet is moving into a coil, and the voltmeter shows a reading. Which change makes the reading drop to zero?
A magnet is moved in and out of a coil wired to a voltmeter. Which statement about the induced voltage is correct?