A magnetic flux through a circuit increases linearly with time, then the absolute value of the induced e.m.f
A) increases because the flux is increasing
B) decreases because according to Lenz's law it opposes the original increase of the flux
C) stays the same at all times
That's a strange School Subject.
It's physics
The induced emf in a coil is equal to the negative of the rate of change of magnetic flux ...
So, if the flux increases, the emf decreases, but the absolute value increases.
To determine how the absolute value of the induced e.m.f (electromotive force) changes with the increasing magnetic flux through a circuit, we can use Faraday's law of electromagnetic induction. Faraday's law states that the induced e.m.f is directly proportional to the rate of change of magnetic flux through a circuit.
Mathematically, this can be expressed as:
e.m.f = -dΦ/dt
Where:
- e.m.f is the electromotive force (induced voltage)
- dΦ/dt is the rate of change of the magnetic flux with respect to time
Based on this equation, we can analyze the given scenario. If the magnetic flux through the circuit is increasing linearly with time, it means that the rate of change of magnetic flux (dΦ/dt) is positive.
Now, let's consider the options:
A) Increases because the flux is increasing - This option is partially correct. The induced e.m.f is indeed affected by the increasing flux, but it doesn't necessarily mean that the e.m.f itself is increasing. It depends on the rate of change of the flux.
B) Decreases because according to Lenz's law it opposes the original increase of the flux - This option is the correct explanation. According to Lenz's law, the induced e.m.f always acts in a way that opposes the change in magnetic flux. In this case, since the flux is increasing, the induced e.m.f will act to try to oppose that increase, resulting in a decrease in the e.m.f.
C) Stays the same at all times - This option is incorrect. If the magnetic flux is changing, the induced e.m.f will also change in response to that.
Therefore, the correct answer is B) Decreases because according to Lenz's law it opposes the original increase of the flux.