Question

A magnet takes a minute to make $30$ oscillations in a magnetic field. If the field strength is doubled, then the time period of oscillation (in sec) is

• A. $\sqrt{2}$
• B. $2\sqrt{2}$
• C. $\frac{\sqrt{3}}{2}$
• D. $\sqrt{3}$
• E. $2$

Answer 1

Answer: (A)

$\sqrt{2}$

Time period of oscillation
$T=2\pi \sqrt{\frac{I}{M{B}_H}}$
$\therefore \frac{T_2^2}{T_1^2}=\frac{B_1}{B_2}$
$\frac{T_2^2}{{\left(2\right)}^2}=\frac{B}{2B}$
$T_2^2=\frac{4}{2}$
$T_2=\sqrt{2}s$