Aconducting bar rests on two parallel horizontal rails 50 cm apart forming a square area. the resistance of the bar and the rails is assumed to be constant and equal to 0.05 ω. a uniform magnetic field 0.5 t is perpendicular to the plane of the rails. the value of the field is uniformly reduced to zero in a time of 0.1 s. what is the maximum value of the force acting on the bar during that time?
a. 6.25 nb. 5.75 nc. 2.05 nd. 4.12 ne. 1.00 n

Force = 6.25

so here correct option is a. 6.25

Explanation:

given data

resistance = 0.05 Ω

uniform magnetic field = 0.5 T

time = 0.1 s

to find out

maximum value of the force acting on the bar during that time

solution

we use here Faraday law of induction in the term of current

and solve here for I via the ohms law instead of the emf

That is end up by dividing by resistance

so here I will be

I =   ..............1

I =

I = 25 A

and now l is length of 1 side of square when we solving for the force that is

Force = N*I²*B

Force  = 1 ×25×0.5×0.5

Force = 6.25

so here correct option is a. 6.25