Question

An electric dipole placed in a uniform electric field of magnitude 2 N/C, experiences a maximum torque of magnitude 5 x 10-3 N m. If the charges of the dipole have a magnitude of 2 mC. then the length of the dipole is ​

Answer 1

Answer:

Electric dipole moment, E=4×10

−9

N/C

Angle made by p with a uniform electric field, θ = 30°

Electric field, E=5×10

4

N/C

Torque acting on the dipole:

τ=pEsinθ

=4×10

−9

×5×10

4

×sin30

o

=20×10

−5

×

2

1

=10

−4

Nm

Hence, the magnitude of the torque acting on the dipole is 10

−4

N m.

Answer 2

Answer:

So, the length of the dipole is 1.2m.

Explanation:

The torque acting on the dipole =PEsinФ.

A dipole experiences a maximum torque when Ф=90°.

The maximum torque is then equal to PE.

5×$10^{-3} =P$×2

P=2.5×$10^{-3}$Cm

By the formula

$P=qd$

2.5×$10^{-3}$=2×$10^{-3}$×d

$d=1.2m$

So, the length of the dipole is 1.2m.