Magnetic Effect of Current

• Oersted's discovery — compass needle deflects near wire carrying current.
• Current produces magnetic field around conductor.
• Electromagnet — coil of wire around iron nail; strong when current flows.
• Applications: electric bell, crane lifting scrap iron, MRI (advanced mention).
• Right-hand rule (intro) — thumb = current, fingers curl = field direction.
• NCERT Activity — compass near straight wire and coil.

Level 1 — Core idea

1. Magnetic effect — moving charges (current) create magnetism.

2. Compass deflection — reverses when current direction reversed.

3. Electromagnet — temporary magnet; strength ↑ with more turns and current.

Level 2 — Process and representation

1. Diagram (text) — battery → coil around nail → switch; nails pick up pins when ON.

2. Electric bell — electromagnet attracts armature, hammer hits gong, circuit breaks, repeats.

3. NCERT Activity 14.7 — compass near current-carrying wire on cardboard.

Level 3 — Applications and NCERT links

1. Real world — junkyard electromagnet crane; doorbells in apartments.

2. Permanent vs electromagnet — electromagnet can switch off.

3. Safety — pacemakers sensitive to strong fields (note only).

NCERT Activity: Making an electromagnet with nail and coil

Materials: iron nail (~8 cm), insulated copper wire (~2 m), cell, switch, small pins.
Step 1 — Wind 50–100 turns of wire along nail leaving free ends.
Step 2 — Connect wire ends to cell through switch (series).
Step 3 — Place pins near nail tip — pins stick when switch ON.
Step 4 — Switch OFF — pins fall (magnetism lost).
Step 5 — Increase turns — more pins picked up.
Step 6 — Reverse cell connections — compass near wire shows field direction reverses.
Step 7 — Do not leave connected long — cell drains, wire may heat.
Conclusion: electric current through coil magnetises iron nail temporarily.

• Who discovered magnetic effect of electric current?
• What happens to compass needle near current-carrying wire?
• Name two devices using electromagnets.
• How is electromagnet different from permanent magnet?
• What material should the core of an electromagnet be?
• What did Oersted observe?

Open the Practice tab for graded questions on Magnetic Effect of Current.