when the north pole of a bar magnet is moved into a solenoid, the needle on a galvanometer attached to the…
when the north pole of a bar magnet is moved into a solenoid, the needle on a galvanometer attached to the solenoid moves to the left, indicating that a current is produced. the magnet is then pulled out at a faster speed. what will be the result?\no a larger current in the same direction\no a larger current in the opposite direction\no a smaller current in the same direction\no a smaller current in the opposite direction
Answer
Explanation:
Step1: Recall Faraday's law
According to Faraday's law of electromagnetic - induction, the induced emf ($\epsilon$) is given by $\epsilon=-N\frac{\Delta\Phi}{\Delta t}$, where $N$ is the number of turns in the solenoid, $\Delta\Phi$ is the change in magnetic flux, and $\Delta t$ is the time interval.
Step2: Analyze the effect of speed
When the magnet is pulled out faster, $\Delta t$ is smaller. Since $\epsilon=-N\frac{\Delta\Phi}{\Delta t}$, a smaller $\Delta t$ for the same $\Delta\Phi$ (magnitude - wise) results in a larger induced emf.
Step3: Determine the direction
When the magnet is moved into the solenoid, a current is induced. When the magnet is pulled out, the change in magnetic - flux is in the opposite sense compared to when it was moved in. According to Lenz's law, the induced current will be in the opposite direction to oppose the change in magnetic flux.
Answer:
B. a larger current in the opposite direction