**The Motor Effect – Practice**

**Questions:**

1) A conductor with a length of 8cm carries a current of 0.0025 A. Calculate the magnitude of the force acting on it when it is in a magnetic field with a strength 0.5 T if:

a) the conductor is at right angles to the field

b) the conductor makes an angle of 62° with the field

c) the conductor is parallel with the field

2) A power line runs from east to west and carries a current of 250 A. The length of the power line is 75m and a force of 0.9375 N is created as a result of the Earth’s magnetic field. Calculate the strength of the Earth’s magnetic field at this position (assume the power line and the Earth’s magnetic field are perpendicular):

3) A conductor with a length of 15cm carries a current of 10 mA in a magnetic field with a strength 0.2 T. If the force acting on the wire is 2×10-4 N, what is the angle between the conductor and the magnetic field?

4) The diagrams below illustrate several magnetic field lines and a wire with a current flowing through it in the direction indicated. Use the right hand palm rule to determine the direction of the force acting on the wire:

a)

b)

**Quick Answers:**

1a) 1 × 10^{-4} N b) 9 × 10^{-5} N c) 0 N

2) 5 × 10^{-5} N

3) 41.8°

4a) into page b) up

**Worked Answers:**