CBSE Class 10 Science 2022 · Paper 31/6/3 · Question 14

(a) Coil-1, connected to the battery and the key, is the primary coil; Coil-2, connected to the galvanometer, is the secondary coil. (b) Electromagnetic induction: the process by which a changing magnetic field in a conductor induces a current in another conductor. (A potential difference is induced in a coil whenever the magnetic field linked with it changes.) (c)(i) On closing (or opening) the key, the current in coil-1 rises (or falls), so the magnetic field it produces, and hence the magnetic field lines linked with coil-2, change. This change induces a potential difference and a current in coil-2, which deflects the galvanometer for a moment. When the current in coil-1 becomes steady, the field stops changing, and the induced current and the deflection fall to zero. OR (c)(ii) (I) When the N-pole is pushed into the coil, the galvanometer needle deflects momentarily, because the moving magnet changes the magnetic field linked with the coil and a current is induced in it. (II) When the magnet is held stationary inside the coil, there is no deflection, because the magnetic field linked with the coil does not change and no current is induced.