AP EAMCET202018 Sep 2020Evening ShiftPhysicsElectrostaticsActual
Two opposite and equal charges each of magnitude (4 10⁻⁸ C ) form a dipole. Their separation is (2 10⁻² ~cm ). When this dipole is placed in an external electric field (4 10^8 NC ⁻¹ ), then the value of maximum torque and the work done in rotating it through (180^ ) respectively will be
Options
- A(64 10⁻⁴ Nm ) and (64 10⁻⁴ ~J )
- B(32 10⁻⁴ Nm ) and (32 10⁻⁴ ~J )
- C(64 10⁻⁴ Nm ) and (32 10⁻⁴ ~J )
- D(32 10⁻⁴ Nm ) and (64 10⁻⁴ ~J )
Correct answer
D. (32 10⁻⁴ Nm ) and (64 10⁻⁴ ~J )
Step-by-step solution
Separation between the electric dipole. (2 a=2 10⁻² ~cm =2 10⁻⁴ ~m ) ( ) Electric dipole moment, (p=q 2 a ) (=4 10⁻⁸ 2 10⁻⁴=8 10⁻¹² C - m ) ( ) Maximum torque ( ( =90^ ) ) is given as, ( aligned _ & =p E 90^ =p E & =8 10⁻¹² 4 10^8=32 10⁻⁴ ~N - m aligned ) Work done in rotating through (180^ ) is given as ( aligned W & =p E ( ₁- ₂ ) & =8 10⁻¹² 4 10^8 ( 0^ - 180^ ) & =64 10⁻⁴ ~J aligned )