Answer:
Step-by-step explanation:
Let magnetic force F acts towards right and the string makes an angle of θ with the vertical in equilibrium .Let T be tension in equilibrium
T cos θ = mg
T sin θ = F
Dividing
Tan θ = F / mg
F = mg Tanθ
= 51.5 x 9.8 x 10⁻³ x 26 / 20.8 Tanθ = 26 / 20.8 )
= 630.875 X 10⁻³ N