Q6 of 32 Page 33

The self-inductance L of a solenoid of length l and area of cross-section A, with a fixed number of turns N increases as

Let’s first see the formula of self-inductance i.e.


where N is the no. of turns, A is the area of loop, l is the length,


μ0 is the magnetic permeability of free space and μ is the permeability of the medium.


In this formula μ & N are fixed so we can say that L is directly proportional to A means as A Increases L also increases and L is inversely proportional to l means as l increases L decreases or vice versa.


So from above conclusion we can directly say that options (a), (c), (d) are wrong.


Therefore, option (b) is correct answer.

More from this chapter

All 32 →
4

There are two coils A and B as shown in Fig 6.2. A current starts flowing in B as shown, when A is moved towards B and stops when A stops moving. The current in A is counterclockwise. B is kept stationary when A moves. We can infer that


 5

Same as problem 4 except the coil A is made to rotate about a vertical axis (Fig 6.3). No current flows in B if A is at rest. The current in coil A, when the current in B (at t = 0) is counterclockwise and the coil A is as shown at this instant, t = 0, is


 7

A metal plate is getting heated. It can be because

 8

An e.m.f is produced in a coil, which is not connected to an external voltage source. This can be due to