Maximum Torque on an Electric Dipole – Rankers Physics

Electric Dipole: Practice Problem & Solution

An electric dipole consisting of two opposite charges of \( 2 \times 10^{-6}\text{ C} \) each separated by a distance of 3 cm is placed in an electric field of \( 2 \times 10^5\text{ N/C} \). The maximum torque on the dipole will be:
\( 12 \times 10^{-1}\text{ Nm} \)
\( 12 \times 10^{-3}\text{ Nm} \)
\( 24 \times 10^{-1}\text{ Nm} \)
\( 24 \times 10^{-3}\text{ Nm} \)

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Electric Dipole. Understanding the underlying formula is key to arriving at the correct answer below:

Maximum torque on a dipole in a uniform electric field is \( \tau_{max} = pE = (q \cdot 2l)E \). Substituting the given values: \( \tau_{max} = (2 \times 10^{-6}\text{ C} \times 0.03\text{ m}) \times (2 \times 10^5\text{ N/C}) = 12 \times 10^{-3}\text{ Nm} \).

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