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

Respuesta :

Answer:

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,[tex]N_2=N[/tex]

Number of turns in first solenoid,[tex]N_1=2 N[/tex]

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

Self- inductance,L=[tex]\frac{\mu_0N^2A}{l}[/tex]

Using the formula

Self- inductance of one solenoid,[tex]L_1=\frac{\mu_0(2N)^2A}{l}=\frac{\mu_04N^2A}{l}[/tex]

Self-inductance of second solenoid,[tex]L_2=\frac{\mu_0N^2A}{l}[/tex]

[tex]\frac{L_2}{L_1}=\frac{N^2}{4N^2}=\frac{1}{4}[/tex]

[tex]L_2:L_1=1:4[/tex]

Hence, option b is true.

Answer:

option (b)

Explanation:

number of turns in the first solenoid, N1 = N

number of turns in the second solenoid, N2 = 2N

Let the current is i and the length is l and the area of crossection of the solenoid is A.

The formula for the self inductance of the solenoid is

[tex]L=\frac{\mu _{0}N^2\times A}{l}[/tex]

It means the self inductance of the solenoid is directly proportional to the square of number of turns.

So, [tex]\frac{L_{1}}{L_{2}}=\frac{N^{2}}{4N^{2}}[/tex]

L1 : L2 = 1 : 4

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