Temporary Magnets

Q.

Magnets which behave as magnets only while on passing electric current in a coil wrapped around them.

Q.

In an electric bell, striker is attracted by a/an__________.

1. bar magnet

2. cylindrical magnet

3. electromagnet

4. horseshoe magnet

Q.

Which kind of magnet can be stronger than a permanent magnet?

1. Bar Magnet

2. Horse Shoe Magnet

3. Electromagnet

4. None of these

Q.

An electromagnet is used in

1. Electric oven

2. Ammeter

3. Electric bell

4. radio set

Q.

An electromagnet made up of soft iron retains its magnetism after the electric current is turned off.

1. True
2. False

Q.

Differentiate between following:

Permanent magnet and temporary magnet

Q.

A permanent magnet creates its own continual magnetic field.

1. Repels

2. Attracts

Q.

Electromagnets are permanent magnets.

1. True

2. False

Q.

Material A gets magnetised under the influence of external magnetic field while material B does not get magnetised. Material A retains the acquired magnetism for a long time. Material C magnetises under the influence of a magnetic field and does not retain it for a long time. Which of them is the most suitable to make electromagnets?

1. Both A and B

2. B

3. A

4. C

Q.

Which of the following is not true about electromagnets?

1. The polarity can be changed

2. The magnetic property is due to current

3. The strength cannot be changed

4. Electromagnets are temporary magnets

Q.

Electromagnets are permanent magnets.

1. False

2. True

Q. Which of the following energy conversion takes place in an electric bell?

1. Electrical energy to mechanical energy
2. Mechanical energy to sound energy
3. Electrical energy to sound energy
4. Electrical energy to magnetic energy

Q.

Which of the following statements about an electromagnet is NOT true?

1. Insulated wire is wound around it.

2. It works only in the presence of electricity.

3. It is used in fans and radio.

4. It is a permanent magnet.

Q.

A magnetic needle which is kept near a conductor gets deflected when current is passed through the conductor.

1. True
2. False

Q.

A current carrying conductor behaves like a/an___________.

1. barometer

2. galvanometer

3. electromagnet

4. permanent magnet

Q.

For making a strong electromagnet, the material of the core should be:

1. Soft iron

2. Brass

3. Copper

4. Steel

Q.

Which of the following produces magnetic field as well as respond to external magnetic field?

1. Only magnets.

2. Only current carrying wires.

3. none of these

4. Magnets and current carrying wires

Q.

Which appliance does not use an electromagnet?

1. T.V.

2. Electric Heater

3. Radio

4. Electric Bell