PHYSICS CH5 Magnetism and Electromagnetism Science - PHYSICS CH5 Magnetism and Electromagnetism

The unit of magnetic flux density is ______.

The part of the AC generator that passes the current from the armature coil to the external circuit is ______.

Transformer works on ______.

Which of the following converts electrical energy into mechanical energy?

An electric generator converts

State whether true or false. If false, correct the statement.

In a step down transformer the number of turns in primary coil is greater than that of the number of turns in the secondary coil.

• True

• False

State whether true or false. If false, correct the statement.

A transformer can step up direct current.

• True

• False

State whether true or false. If false, correct the statement.

The speed of rotation of an electric motor can be increased by decreasing the area of the coil.

• True

• False

State whether true or false. If false, correct the statement.

Fleming’s Left hand rule is also known as Dynamo rule.

• True

• False

State whether true or false. If false, correct the statement.

Magnetic field lines always repel each other and do not intersect.

• True

• False

State Faraday’s laws of electromagnetic induction.

Differentiate step up and step down transformer.

State the advantages of ac over dc.

Draw and label the diagram of an AC generator.

List the main parts of an electric motor.

Match the following.

1.	Magnetic material	a)	Oersted
2.	Non-magnetic material	b)	Iron
3.	Current and magnetism	c)	Induction
4.	Electromagnetic (d) Wood induction	d)	Wood
5.	Electric generator	e)	Faraday

1. Electricity and magnetism	a) Step-down transformer
2. Force on the conductor	b) Hans Christian Oersted
3. Electric bell	c) I L B
4. Ns <Np	d) Electromagnet

 

Draw a neat diagram of an AC generator and explain its working.

Explain two types of transformer.

Explain the principle, construction and working of a dc motor.

Explain the properties of magnetic lines of force.

Explain the application of electromagnets in the field of medical system.

A device for producing electric current is ______.

An electric motor converts ______.

Devices which is used to convert high alternating current to low alternating current is ______.

The SI Unit of magnetic field induction is ______.

No force acts in a current carrying conductor when it is to the magnetic field.

A portable radio has a built in transformer so that it can work from the mains instead of batteries. Is this a step up or step down transformer? Give reason.

Define magnetic flux density.

A galvanometer is an instrument that can detect the presence of a current is a circuit.

The magnetic poles always exist in pairs.

The pole of a freely suspended magnet which points towards the north is called the south pole and what points towards south is celled north pole.

Permanent magnets are made of hard magnetic materials like alnico.

An electric generator works on the principle of electromagnetic induction.