CBSE 2025 · Region 2 · Set 1 · Q24 · 3 marks
(a)State Lenz's law.(b)In the given figure:
(i)Identify the machine.(ii)Name the parts P and Q and R of the machine.(iii)Give the polarities of the magnetic poles.(iv)Write the two ways of increasing the output voltage.
(a)
State Lenz's law.
(b)
In the given figure:
(i)
Identify the machine.
(ii)
Name the parts P and Q and R of the machine.
(iii)
Give the polarities of the magnetic poles.
(iv)
Write the two ways of increasing the output voltage.
Marking-scheme solution
(a)
Lenz's law – The polarity of induced emf is such that it tends to produce a current which opposes the change in magnetic flux that produced it.
(i)
AC generator
(ii)
P – Slip rings
Q – Carbon brushes
R – Armature coil
(iii)
Left side of the magnet is North & right side is South or vice-versa.
(iv)
By increasing the number of turns in the armature coil.
By increasing the speed of rotation of the armature coil.
By increasing the strength of the magnetic field B.
Electromagnetic InductionLenz’s Law and Conservation of EnergyUnderstandshort_answermedium
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CBSE Class 12 Physics past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.