Question

11. Figure shows the top view of a rod that can slide
without friction. The resistor is 6.0 ohm and a 2.5T
uniform magnetic field is directed perpendicularly
downward into paper. If length of moving rod is 1.2m
and it moves with a constant speed of 2 m/s then
the rate at which energy is delivered to the resistor
is
(1) 12 W
(3) 3 W
(2) 6 W
(4) 20 W​

Answer 1

Power = Fv

F = BIL

I = E/R

E = BLv

E = 2.5 x 1.2 x 2 = 6V

I= 6/6 = 1A

F = 2.5 x 1 x 1.2

F = 3N

Power = 3 x 2 = 6W

Answer 2

Given:

Resistor = 6.0 ohm

length of rod =1.2m

speed = 2 m/s

uniform magnetic field = 2.5T

To Find:

the rate at which energy is delivered to the resistor

Explanation:

e = Brl

  = 2.5×2×1.2

  = 6v

i = e/R = 6/6

 = 1Δ

F =F(mg) = iBl

  = 1×2.5×1.2

  = 3 N

P = i²r

  = 6 w

p(F) = F×V

      = 3×2

     = 6w

Answer = 6w Option (2) is correct.