Q40 of 238 Page 84

For the coil in the diagram below, when the switch is pressed:

(a) What is the polarity of end A?


(b) Which way will the compass point then?


(a) End A becomes south pole. This is because from the end at the current flows in clockwise direction.

(b) The movement of the compass needle is away form the end B. As end B is the north pole.


More from this chapter

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38

The figure shows a solenoid wound on a core of soft iron. Will the end A be a N pole or S pole when the current flows in the direction shown?

 39

A current-carrying straight wire is held in exactly vertical position. H the current passes through this wire in the vertically upward direction, what is the direction of magnetic field produced by it? Name the rule used to find out the direction of magnetic field.

 41

A current flows downwards in a wire that passes vertically through a table top. Will the magnetic field lines around it go clockwise or anticlockwise when viewed from above the table?

 42

The directions of current flowing in the coil of an electromagnet at its two ends X and Y are as shown below:




(a) What is the polarity of end X?


(b) What is the polarity of end Y?


(c) Name and state the rule which you have used to determine the polarities.