A long solenoid has `200 turns per cm` and carries a current `i`. The magnetic field at its centre is `6.28xx10^(-2) weber//cm^(2)`. Another long soloenoid has `100 turns per cm` and it carries a current `(i)/(3)`. The value of the magnetic field at its centre is

Options

A. `1.05 xx 10^(-3)Wb//m^(2)`
B. `1.05 xx 10^(-4)Wb//m^(2)`
C. `1.05 xx 10^(-2)Wb//m^(2)`
D. `1.05 xx 10^(-5)Wb//m^(2)`

Answer

C

Explanation

For a solenoid, `B=mu_0nI therefore (B_2)/(B_1)=(mu_0n_2I_2)/(mu_0n_1I_1)=(100)/(200) xx (I/(3I))=1/6 therefore B_2=(B_1)/6=(6.28 xx 10^(-2))/6 -=1.05 xx 10^(-2)Wb//m^(2)`