Two solenoids have the same cross-sectional area and length, but the first one has twice as many turns er unit length as the second.

The ratio of the self-inductance of the second solenoid to that of the first is :

a. 1:2

b. 1:4

c. 2:1

d. 4:1

e. 1:1

b:1:4

Explanation:

We are given that two solenoid.

Suppose ,the length of each solenoid=l

Cross-sectional area of each solenoid=A

Let , number of turns in in second  solenoid,

Number of turns in first solenoid,

We have to find the ratio of self-inductance of the second solenoid to that of the first.

Self- inductance,L=

Using the formula

Self- inductance of one solenoid,

Self-inductance of second solenoid,

Hence, option b is true.

radiation warms things up temp rises convection currents air circ windy weather