# Homework Help: Electricity homework problem

1. Apr 22, 2012

### spaghetti3451

1. The problem statement, all variables and given/known data

(i) What is the strength and direction of the force per unit length acting on a straight conductor carrying an electrical current, I, in a magnetic field, B?

(ii) The figure below shows a square frame of aluminium set at an angle θ to the direction of a strong static magnetic field, B, parallel to the x-axis (the y-axis is vertical). The frame has sides of length L and the arms have cross-sectional area A, with L >> √A. Write down expressions for the electrical resistance (for currents flowing around the frame) and the total mass if the density and conductivity of aluminium are ρ and σ respectively.

(iii) left out for the moment

2. Relevant equations

3. The attempt at a solution

(i) F = B x Il,
so F/l = BIsinφ, where φ is the angle between the direction of force and the length of the conductor and the force acts in a direction which is perpendicular to the magnetic field and the length of the conductor.

(ii) Electrical resistance R = L/σA

Total mass = ρV = ???

Any comments would be greatly appreciated.

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Last edited: Apr 22, 2012
2. Apr 22, 2012

### Quinzio

Re: Electricity

Well, V=LA.

3. Apr 22, 2012

### spaghetti3451

Re: Electricity

Well, I know that but the problem is part of the frame is missing, so don't know how to take that into account.