Physics · Electromagnetic Induction · NEET
It depends on which pole approaches and from which side you look. Rule: the coil ALWAYS opposes what the magnet is doing. If the N-pole approaches, flux increases, so the coil's near face must become a N-pole to repel it. Viewed from the magnet's side, a N-face means the current runs anticlockwise. Always fix your viewpoint first (say, looking from the magnet toward the coil), then apply the pole rule. NCERT states exactly this: N-pole pushed toward the coil gives a counter-clockwise (anticlockwise) current as seen from the magnet's side.
The face pointing at the approaching magnet. If a N-pole approaches, the coil's near face becomes N (like poles repel = oppose the approach). If a S-pole approaches, the near face becomes S. This is Lenz's law: the coil resists the change. Once you know the face polarity, use the clock rule: current anticlockwise (seen facing that face) = N-pole; clockwise = S-pole.
It attracts it. Moving away means flux is decreasing, and the coil opposes the decrease by trying to hold the magnet back. So the coil's near face becomes the OPPOSITE pole to the leaving pole: a leaving N-pole faces an induced S-face (unlike poles attract). Viewed from the magnet's side, a S-face means the induced current is clockwise. NCERT: withdrawing the N-pole gives a clockwise current and a S-pole facing the receding magnet.
Step 1: Decide if flux through the coil is increasing (magnet approaching) or decreasing (leaving). Step 2: The induced current opposes this change. Increasing flux to the right means induced field points left inside the coil, and vice versa. Step 3: Use the right-hand rule (curl fingers along the current, thumb points along the induced B) to convert that field direction into a current sense. Step 4: Read it as clockwise/anticlockwise from your chosen viewpoint. The face-pole shortcut (approach = repel, leave = attract) is faster for NEET MCQs.
Yes, it reverses the answer. Swapping the pole swaps the induced face and therefore the current direction. But the PRINCIPLE never changes: approaching = repel (same-type face), leaving = attract (opposite-type face). If a question swaps the pole AND the direction of motion, work through both changes carefully; two reversals can cancel and give the same current sense.
No induced current. Induced current needs a CHANGING flux (relative motion or a changing field). A stationary magnet gives constant flux, so dΦ/dt = 0 and the induced emf is zero. The galvanometer deflects only while the magnet is moving, exactly as NCERT's Experiment 6.1 shows.
A strong bar magnet is moving towards solenoid-2 from solenoid-1 (magnet's N-pole leaves solenoid-1 and approaches solenoid-2). Using terminals A,B on solenoid-1 and C,D on solenoid-2, the direction of induced current in solenoid-1 and in solenoid-2 respectively are:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Lenz's law: the induced current always flows in the direction that opposes the change in magnetic flux causing it. Practically, an approaching magnet is repelled and a leaving magnet is attracted by the coil.
Anticlockwise, when viewed from the magnet's side. Increasing flux from a N-pole makes the coil's near face a N-pole (to repel), and a N-face corresponds to anticlockwise current as you look at it.
Induced emf = rate of change of flux (ε = -N dΦ/dt). A stationary magnet keeps flux constant, so dΦ/dt = 0 and no current flows. Only the change matters, not the presence of the field.
No — it enforces it. The coil opposes the magnet's motion, so you must do work to push or pull the magnet. That mechanical work is what becomes the electrical energy of the induced current.
Here the current comes from a changing flux due to the magnet moving relative to a fixed coil. Motional emf comes from a conductor of length l moving with speed v across a field, giving ε = Bvl. Both obey Lenz's law for direction.
