(a) Explain what is meant by a magnetic field

(b)(i) Describe an experiment to show that a magnetic field exists around a straight wire carrying current

(ii) Draw a labelled diagram showing the pattern and direction of the magnetic field rroduced around the wire. (Neglect the earth's magnetic field).

(c) Sketch the magnetic field due to two straight parallel wires carrying current in the same direction. Indicate the neutral point in the field

(d) Explain, with the aid of a labelled diagram, how a delicate magnetic material could be protected from the earth's magnetic field.

(a) State the laws of electromagnetic induction

(b) Explain how one of the laws illustrates the principle of conservation of energy

(c)(i) Draw a labelled diagram of a simple d.c. electric motor and explain how it works.

(ii) State two reasons why the efficiency of an electric motor is less than 100%. 

The limiting frictional force between two surface depends on

I. the gaseous reaction between the surfaces

II. the nature of the surfaces in contact

III. the relative velocity between the surfaces

If a body moves with a constant speed and at the same time undergoes an acceleration, its motion is said to be

When blue and green colours of light are mixed, the resultant colour is