Motor effect

Which one of the following materials is NOT magnetic?
1. Steel
2. Carbon
3. Cobalt
4. Nickel
A carbon rod is placed in a magnetic field at 90 degrees to its axis. A current flows through the carbon rod. Which one of these happens to the rod?
1. Nothing.
2. It gets attracted to the north pole of the magnet.
3. It moves in the same direction as the current
4. It moves at 90 degrees to the current and 90 degrees to the magnetic field.
The rule that tells us the direction of movement in the motor effect is:
1. Fleming's Left Hand Rule
2. Fleming's Right Hand Rule
3. Fleming's Left Foot Rule
4. Fleming's Right Foot Rule
In a motor effect demonstration the carbon rod moves from left to right. Which one of these changes would make the rod move from right to left?
1. Turning the rod round.
2. Reversing the current only.
3. Reversing both the current and the magnetic field.
4. Using a copper rod.
The magnetic field in the motor effect demonstration is reversed. What effect will this have on the rod?
1. The rod will not move.
2. The rod moves from left to right as before.
3. The rod now moves from right to left, i.e. in the opposite direction.
4. The rod will be attracted to the magnet.
In the motor effect demonstration, the magnet is turned so that the field goes from left to right instead of downwards. A current passes through the carbon rod. What happens now?
1. The carbon rod stays where it is.
2. The carbon rod moves from left to right.
3. The carbon rod moves from right to left.
4. The carbon rod turns so that it points towards the north pole of the magnet.
In the motor effect, the maximum force on a wire occurs when:
1. The current is parallel to the magnetic field
2. The current is at 30 degrees to the magnetic field
3. The current is at 45 degrees to the magnetic field
4. The current is at 90 degrees to the magnetic field
Which one of these will NOT increase the force on a wire in a magnetic field?
1. Increasing the current and keeping the magnetic field strength the same.
2. Increasing the magnetic field strength and keeping the current the same.
3. Increasing both the current and the magnetic field strength.
4. Keeping both the magnetic field strength the same, but changing the material of the wire.
Which one of these applications does NOT use the motor effect?
1. A small motor driving a fan in a computer.
2. A loudspeaker
3. A moving coil ammeter
4. The heating element in a kettle.
Which one of these changes would increase the force on the armature of a simple electric motor?
1. Increasing the size of the commutator
2. Increasing the number of turns of wire in the armature.
3. Reversing the magnetic field
4. Reducing the magnetic field strength.

Motor Effect

Quiz