Induction in a Coil?
A coil of insulated copper wire is connected to an ammeter and a galvanometer in series. When a magnet is brought near the coil, the galvanometer shows a deflection, but the ammeter does not. Explain the reason behind this observation, and suggest a method to improve the sensitivity of the galvanometer reading.
1 Answer
📌 CONCEPT: Electromagnetic induction occurs when a conductor coil is exposed to a changing magnetic field, inducing an electric current in the coil.
📐 RULE / FORMULA: The induced emf (ε) in a coil is given by Faraday's law of induction, ε = -N(dΦ/dt), where N is the number of turns and Φ is the magnetic flux.
💡 WORKED EXAMPLE: Consider a coil of 50 turns connected to a galvanometer and ammeter. When a magnet is brought near the coil at a constant speed, the magnetic flux through the coil changes, inducing an emf and causing a deflection in the galvanometer. The ammeter shows no deflection because the induced current is very small and the resistance of the galvanometer is much higher than the coil's resistance.
⚠️ COMMON MISTAKE: Students often confuse electromagnetic induction with electromagnetic attraction or repulsion, which are phenomena related to magnetic forces rather than induced electric currents.
03 Oct 26
🔗 More from Electromagnetic Induction
Practice this chapter
Get AI-generated board exam questions, track your mastery, and identify weak spots.
Start Free →