Question

Assume that the pictured magnet is being moved into the solenoid. If the polarity of the magnet is reversed and then moved into the solenoid, what happens? *

Answer 1

The direction of induced emf is revered and hence the direction of the induced current.

Step-by-step explanation:

If the polarity of the magnet is reversed, the direction if the field lines through the solenoid is also reversed, which according to Faraday's law means

`\varepsilon =N(d\Phi)/(dt) \rightarrow -N(d\Phi)/(dt)`

in other words, the direction of the magnetic flux is revered, and therefore, the direction of the induced emf is also revered.

Furthermore, according to Ohm's law

`I = (\varepsilon)/(R)`

which tells us that if the induced emf changes sign (is reversed)

`I = -(\varepsilon)/(R)`

the direction of the induced current is also reversed.