Question

Two coaxial solenoids of different radii carry current I in the same direction. Let F₁ be the magnetic force on the inner solenoid due to the outer one and F₂ be the magnetic force on the outer solenoid due to the inner one. Then

(a) F₁=F₂=0

(b) F₁ is radialiy inwards and F₂ is radially outwards

(c) F₁ is radially inwards and F₂ = 0

(d) F₁ is radially outwards and F₂ = 0

Answer 1

Correct Option(a) F₁=F₂=0

Explanation:

Consider the two coaxial solenoids, Due to one of the solenoids magnetic field at the centre of the other can be assumed to be constant.

Due to symmetry, forces on the upper and lower part of a solenoid will be equal and opposite and hence resultant is zero

Therefore, F₁ = F₂ = 0