Magnetism and Electricity

Question 1

What method is the most effective to test the strength of a magnet?

Answer 1

Count the number of paper clips the magnet will hold

Question 2

The Earth has its own magnetic field with a magnetic…

Answer 2

S Pole at its geographic North Pole

Question 3

What arrangement would produce the strongest electromagnet?

Answer 3

High current, high number of coils, iron core

Question 4

What does not make a D.C. motor in a battery powered car run faster?

Answer 4

Increasing the size of the car’s road wheels

Question 5

What two parts would you find in an electric bell?
A) a coiled spring
B) a plastic core
C) an iron armature
D) a hammer and bell

Answer 5

An iron armature and a hammer and bell

Question 6

In a simple D.C. motor, how can the movement be stopped and how can it be reversed?

Answer 6

It can be stopped by stopping the current and it can be reversed by switching the Poles of the battery

Question 7

Explain the difference between a permanent and temporary magnet

Answer 7

A permanent magnet is when it will be a magnet on its own, all the domains are aligned. A temporary magnet means it can only be a magnet if it is attached to a permanent magnet so the domains are not aligned

Question 8

Describe how an electric bell works

Answer 8

When the switch is closed (the buzzer is pressed), a current flows through the circuit. A magnetic field is now generated in the electromagnet. The iron contact is attracted to the magnetic field and moves towards the electromagnet. The clapper hits the bell. Now the circuit is broken, the current stops flowing and the electromagnet switches off. The iron contact is no longer attracted and springs back. The circuit is now complete and the process repeats.