SPM Physics

SPM Questions on electromagnet: 2004 -05

1 The diagram shows an arrangement of apparatus to study the pattern of magnetic fields which are formed when current flows through conductors:

Answer: B

To answer this one, 1st determine the direction of current entering the cardboard for both conductors.

For each case, apply right hand thumb rules to determine the direction of magnetic field.Look at diagram below:

2. The diagram shows an electromagnet.

Which factor does not influence the strength of the electromagnet ?

A Material used for the wire

B Material used for insulator of the wire

C Number of turns of wire

D Current flowing in the wire..

Answer:B, coz insulator wont affect the magnetic field strength

This question asked for a wrong answer..so beware, always underline important phrase like, does not.

The other answers will influence the strength of electromagnet;

- A: different wire materials used would give dfferent resistance which then affect amount of current flows.

strength of magnetic field depends on current flows.

- C: No. of turns wire...bigger number of turn produce stronger magnetic field

- D:amount of current...higher current give stronger magnetic field