Question

A sample of $HCl$ gas is placed in an electric field of $3 \times 10^{4} \,NC ^{-1}$. The dipole moment of each $HCl$ molecule is $6 \times 10^{-30} \,Cm$. The maximum torque that can act on a molecule is

• A. $2 \times 10^{-34}\, C ^{2} \,Nm ^{-1}$
• B. $2 \times 10^{-34}\, Nm$
• C. $18 \times 10^{-26}\, Nm$
• D. $0.5 \times 10^{34} \,C ^{-2}\, Nm ^{-1}$

Answer 1

Answer: (C)

Torque, $ \tau =p \times E $
$ \tau_{\max } =p E $
$=6 \times 10^{-30} \times 3 \times 10^{4} $
$=18 \times 10^{-26} \,Nm $