Question
A class is designing a d.c. motor. To achieve a greater turning effect, three suggestions are made.
Have a larger current in the coil of the motor.
Have a stronger magnet in the motor.
Put a larger number of turns on the coil.
Which suggestions will help to increase the turning effect?
A 1, 2 and 3
B 1 and 2 only
C 1 and 3 only
D 2 and 3 only
Answer/Explanation
Ans: A
Question
The diagram shows a simple d.c. electric motor which is rotating.
Which change makes the motor rotate more quickly?
increasing the number of turns on the coil
removing the magnets
reversing the battery
reversing the polarity of the magnets
Answer/Explanation
Ans: A
We can let the d.c. motor run quickly by two ways :
(a) by adding more powerful magnet so that it can add more torque .
(b) by increasing the current flowing through the coil. It can be done by increasing the number of turns of coil .
So, option (A) is correct