# Homework Help: Calculate the work done when a conductor moves through a mag

1. Mar 1, 2016

### DevonZA

1. The problem statement, all variables and given/known data
A conductor 7.5m long, is moved at a uniform speed at right angle to its length and to a uniform magnetic field. The density of the magnetic field is 0.64T. The emf generated in the conductor is 36V and the conductor is part of the closed circuit that has a resistance of 4.3ohms. Calculate the velocity at which the conductor moves through the magnetic field? Calculate the work done when the conductor has moved 92.3cm through the magnetic field.

2. Relevant equations
V=-d(BA)/dt
V=-Bls

3. The attempt at a solution
s=-V/Bl
s=-36/0.64x7.5
=7.5m/s

I am not sure how to calculate the work done but the answer is one of the following :
1. 36.001J
2. 35.333J
3. 36.444J
4. 37.092J

2. Mar 1, 2016

The work done will be the energy dissipated by the closed circuit loop.
This loop carries a current = I = 36/4.3 = 8.3721 a. The electrical power in this circuit = VI.
Power = VI = 36(8.3721) = 301.3953
Work = Energy used = Power • time
Where the time for loop to move a distance = 0.932 m at a speed = 7.5 m/s or t = 0.923/7.5 = 0.12307 s
Work = (301.3953)(0.12307) = 37.092 J ANS 4.

3. Mar 1, 2016

### DevonZA

Hi Jim

Thank you so much, makes perfect sense.