AIIMS2017PhysicsElectrostatics
In a certain region of space, electric field is along the z -direction throughout. The magnitude of electric field is however not constant, but increases uniformly along the positive z -direction at the rate of 10^5 ~N C ⁻¹ ~m ⁻¹ . The force experienced by the system having a total dipole moment equal to 10⁻⁷ C m in the negative z -direction is
Options
- A-10⁻² ~N
- B10⁻² ~N
- C10⁻⁴ ~N
- D-10⁻⁴ ~N
Correct answer
A. -10⁻² ~N
Step-by-step solution
Consider an electric dipole with -q charge at A and +q charge at B , placed along z -axis, such that its dipole moment is in negative z direction. i.e., p_ z =-10⁻⁷ Cm The electric field is along positive direction of z -axis, such that d E d z =10^5 NC ⁻¹ ~m ⁻¹ From, F=q d E=(q d z) d E d z =p d E d z Force experienced by the system in the negative z -direction, F=-p (- d E d z )=10⁻⁷ (-10^5 )=-10⁻² ~N