| Directions: In the following questions, a statement of Assertion [A] is followed by a statement of Reason (R). |
| Mark the correct choice as: |
| Assertion [A]: We use a thick wire in the secondary coil of a step down transformer to reduce the production of heat. |
| Reason (R): When the plane of the armature is parallel to the line of force of magnetic field, the magnitude of induced e.m.f, |
A) Both Assertion [A] and Reason (R) are true and Reason (R) is the correct explanation of Assertion [A]
B) Both Assertion [A] and Reason (R) are true but Reason (R) is not the correct explanation of Assertion [A]
C) Assertion [A] is true but Reason (R) is false
D) Assertion [A] is false and Reason (R) is also false
Correct Answer: B
Solution :
(b) A step-down transformer converts electrical energy from a high voltage to low voltage. Accordingly the current in the secondary will be larger than that in the primary. In order to produce less heat in the secondary, we use a wire of lesser resistance i.e., thick wire. We also know that when the plane of the armature is parallel to the lines of force of magnetic field, the rate of change of magnetic flux linked with it is maximum. Therefore the e.m.f. induced in the armature in this orientation is maximum.
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