Question

1.For an angle of zero between the magnetic field and the vector normal to the plane of the coil: (a) What happens to the light bulb as it enters the magnetic field region? Explain. (b) What happens to the light bulb as it moves while it is completely inside the magnetic field? Explain. (c) What happens to the light bulb as it exits the magnetic field region? NOTE: Use Faraday’s Law to explain.

2.For an angle of zero between the magnetic field and the vector normal to the plane of the coil: What happens to the light bulb when the you flip the direction of the magnetic field? Explain using Faraday’s Law.

3.For an angle of zero between the magnetic field and the vector normal to the plane of the coil: What happens to the light bulb when the magnitude of the magnetic field varies? Explain using Faraday’s Law

4.For an angle of zero between the magnetic field and the vector normal to the plane of the coil: What happens to the light bulb when the coil moves vertically? Explain using Faraday’s Law

Answer 1

First of all the expression for the induced emf as per the faraday's law is given as

E = - rate of change of magnetic field

Or

E = -N d(B•A)dt

As where in the question mentioned zero angle between the magnetic field and the area vector or normal vector which means it will give maximum of its flux at this time as cos0° = 1

So that,

E = - BA

Will be use where ever it is necessary.

1.

a) when the bulb enters into the magnetic field then there will be a change in the flux through the coil which induce emf in the bulb and this change is increasing in magnitude but will produce negative emf so that bulb will start glowing as it enters into the field and the intensity is increasing in nature.

b) when the bulb is completely enters into the field then there will not be any change in the magnetic field or we can say that constant magnetic field have zero induce emf so that bulb will not glow in this case.

c) when the bulb starts exiting the region of magnetic field then it will induce again emf as here there is a change in magnetic field but this time change is negative so that the emf induced will be positive and again bulb will starts glowing but in this case the bulb will glow in such a way that its intensity is decreasing in nature.

2. For an angle of zero between the magnetic field and the vector normal to the plane of the coil and by flipping the direction of magnetic field will change the direction of induced current through the bulb only not change its intensity so that it will have same intensity as in case a and c of first question.

Because here angle between the magnetic field and the normal becomes 180°.

3.For an angle of zero between the magnetic field and the vector normal to the plane of the coil and when the magnitude of the magnetic field varies then there will be emf induce everywhere inside the magnetic region because here as per the faraday's law we will get rate of change of magnetic field everywhere so that bulb will glow continuously till it is inside the magnetic field.

4.For an angle of zero between the magnetic field and the vector normal to the plane of the coil and when the coil moves vertically then the angle between magnetic field and area vector becomes 90° which makes the dot product of B and A to zero as Cos90° = 0 hence bulb will not glow at all inside the magnetic field.