Electric Charges and Fields - Result Question 32
32. An electric dipole, consisting of two opposite charges of $2 \times 10^{-6} C$ each separated by a distance $3 cm$ is placed in an electric field of $2 \times 10^{5} N / C$. Torque acting on the dipole is
(a) $12 \times 10^{-1} Nm$
(b) $12 \times 10^{-2} Nm$
(c) $12 \times 10^{-3} Nm$
(d) $12 \times 10^{-4} Nm$
[1995]
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Answer:
Correct Answer: 32. (c)
Solution:
- (c) Charges $(q)=2 \times 10^{-6} C$,
Distance
(d) $=3 cm=3 \times 10^{-2} m$ and
electric field (E)
$=2 \times 10^{5} N / C$.
Torque $(\tau)=pE=qdE$
$T=(2 \times 10^{-6}) \times(3 \times 10^{-2}) \times(2 \times 10^{5})$
$=12 \times 10^{-3} N-m$.
