Question

Find out time period of small oscillations from mean position

• A. $2\pi \sqrt{\frac{l}{g}}$
• B. $2\pi \sqrt{\frac{l}{{(g^2+{\left(\frac{qE}{m}\right)}^2)}^{1/2}}}$
• C. $\frac{1}{2\pi }\sqrt{\frac{l}{g}}$
• D. $\frac{1}{2\pi }\sqrt{\frac{l}{{(g^2+{\left(\frac{qE}{m}\right)}^2)}^{1/2}}}$

Answer 1

Answer: (B)

From FBD,
$Tsin\theta =qE$ ............... (1) where $T$ is the tension in the string.
$Tcos\theta =mg$ ............... (2)
$\therefore tan\theta =\frac{qE}{mg}$
$\theta =ta{n}^{-1}\left(\frac{qE}{mg}\right)$