Correct Answer
D — Flemming’s Right hand rule
Concept Foundation
Electromagnetic induction determines the magnitude of induced EMF through Faraday’s law, while a directional rule is needed when the motion and magnetic-field directions are specified. Fleming’s right-hand rule is the standard generator rule.
Step-by-Step Solution / Reasoning
Hold the thumb, forefinger and middle finger of the right hand mutually perpendicular:
Forefinger: magnetic field direction (N→S)
Thumb: motion of conductor
Middle finger: induced current/EMF direction
Why This Method Works
The rule encodes the vector direction associated with motional EMF. It is therefore suited to generator action, where mechanical motion through a magnetic field induces electrical EMF.
Verification / Cross-Check
Faraday’s law gives magnitude and the existence of induced EMF but, by itself, the named hand-rule answer for direction in this MCQ is Fleming’s right-hand rule. Fleming’s left-hand rule is the motor-force rule.
Concept Extension
Lenz’s law is another fundamental directional principle: the induced effect opposes the change producing it. In machine MCQs, however, Fleming’s right-hand rule is the standard practical generator-direction rule.
Exam Strategy / Takeaway
Right hand = generator; left hand = motor.
