Question

As shown in the figure, a magnet is moved with a fast speed towards a coil at rest. Due to this induced em.f.
induced current and induced charge in the coil is E, I and Q respectively. If the speed of the magnet is
doubled, the incorrect statement is

1)E increases
2)I increases
3)Q remains same
4)Q remains same
​

Answer 1

Given:

As shown in the figure, a magnet is moved with a fast speed towards a coil at rest. Due to this induced em.f. induced current and induced charge in the coil is E, I and Q respectively.

To find:

Incorrect statement.

Calculation:

According to Faraday's Law of Electromagnetic Induction , the induced EMF will be equal to the instantaneous rate of change of magnetic flux.

$\boxed{ \therefore \: E = \dfrac{d \phi}{dt} }$

Now , current will be EMF divided by resistance:

$\boxed{\therefore \:I = \dfrac{E}{r} = \dfrac{(\frac{d \phi}{dt})}{r} }$

Now , charge loan can be calculated by multiplying current with time.

$\boxed{\therefore \:Q = I \times dt = \dfrac{(\frac{d \phi}{dt})}{r} \times dt = \dfrac{ d \phi}{r} }$

So, the charge flown doesn't depend on the rapidity of movement of magnetic.

Hence "charge increases" is the incorrect statement.