Question

A conducting 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?

Answer 1

Force = 6.25 N

Step-by-step explanation:

Given:

Distance between the rails, l = 50cm = 0.5m

since it is forming a square area. thus, area = 0.5² m²

Resistance of the bar = 0.05Ω

Magnetic field, B = 0.5T

Time = 0.1s

Now,

The value for EMF is given as

EMF = (ΔArea x Field) /time

substituting the values in the above equation we get

EMF = (0.5² x 0.5) /0.1 = 1.25 Volts

now,

Current, i = EMF/ Resistance

substituting the values in the above equation we get

i = 1.25/0.05 = 25 A

Now the force is given as:

Force = i x l x B

Force = 25 x 0.5 x 0.5

Force = 6.25 N