Solenoids and Electromagnetism Induction

Question 1

True or false? A solenoid is an example of an electromagnet.

Answer 1

True

The magnetic field around a solenoid can be turned on and off using an electric current

Question 2

Is the magnetic field outside a solenoid stronger or weaker than the magnetic field along the centre of the solenoid?

Answer 2

Weaker
(Inside the solenoid, the field lines around each separate loop of wire point in the same direction, producing a strong field, whereas outside the solenoid the lines overlap and cancel each other out, so the magnetic field is weak.)

Question 3

Why is the magnetic field inside a solenoid stronger than the magnetic field around a straight, current-carrying wire?

Answer 3

The field lines around each loop of wire in a solenoid line up. This results in field lines that are very close together. The closer the field lines, the stronger the magnetic field.

Question 4

Describe how a potential difference in a wire can be induced using a magnetic field.

Answer 4

Move the wire relative to the magnetic field, or change the magnetic field around the wire

Question 5

Give two factors that affect the size of an induced potential difference in a coil of wire

Answer 5

Factors that affect the size of an induced potential difference are: the strength of the magnetic field, the speed of the movement/change in field, and the number of turns per unit length on the coil of wire.

Question 6

The north pole of a bar magnet is slowly pushed into a coil of wire. Explain whether the force between the bar magnet and the coil is attractive or repulsive.

Answer 6

The force between the bar magnet and the coil will be repulsive. The magnetic field created by an induced current acts against the change that made it. So it will act to repel the magnet out of the coil.