⚡ Class 10 Physics Chapter 4: Electric Current and Its Effects

CBSE Board 2026 | Complete Detailed Notes + MCQs + PYQs + Case-Based Questions

🎯 Chapter Weightage for Boards

Expected Questions:

1 Mark MCQs
Assertion-Reason
Case-Based Questions
2 Marks Short Answers
3 Marks Long Answers
Diagram Based Questions

📖 Introduction

Electric current produces different effects when it passes through a conductor.

Main Effects:

Heating Effect of Electric Current
Magnetic Effect of Electric Current

These effects are used in many daily-life appliances.

Examples:

Electric iron
Room heater
Electric bell
Electromagnetic crane
Fuse
MCB

🌟 Heating Effect of Electric Current

When current passes through a wire, heat is produced.

This is called the Heating Effect of Electric Current.

Activity

Connect:

Cell
Switch
Bulb

When current flows, bulb glows and becomes warm.

This shows conversion of electrical energy into heat and light energy.

🌟 Applications of Heating Effect

Electric Iron

Used for ironing clothes.

Working:

Current passes through nichrome wire.

Nichrome becomes hot.

Heat is transferred to iron plate.

Clothes become wrinkle-free.

Room Heater

Converts electrical energy into heat energy.

Contains nichrome heating element.

Electric Toaster

Uses heating effect to toast bread.

Electric Kettle

Uses heating effect to boil water.

🌟 Heating Element

Heating elements are usually made of Nichrome.

Properties of Nichrome

✔ High resistance

✔ High melting point

✔ Does not burn easily

✔ Produces more heat

✔ Long lasting

🌟 Electric Fuse ⭐ Most Important

A fuse is a safety device used to protect appliances from excessive current.

Need of Fuse

Suppose:

Fan requires 2A current.

Suddenly 10A current flows.

Fan may get damaged.

Fuse prevents this damage.

Working of Fuse

When excessive current flows:

Fuse wire heats up.
Fuse melts.
Circuit breaks.
Appliance gets protected.

Characteristics of Fuse Wire

Low melting point
High resistance

🌟 Overloading

Overloading occurs when many appliances are connected to a single socket.

Examples

Heater
AC
Iron
Geyser

Running together can overload the circuit.

🌟 Short Circuit

Occurs when:

Live wire touches neutral wire.

Resistance becomes very low.

Huge current flows.

Can cause fire.

🌟 MCB (Miniature Circuit Breaker)

Modern replacement of fuse.

Advantages

✔ Reusable

✔ Safer

✔ Fast action

✔ Easy operation

🌟 Magnetic Effect of Electric Current

When current passes through a conductor, a magnetic field is produced around it.

This is called Magnetic Effect of Current.

🌟 Hans Christian Oersted's Experiment

In 1820, Oersted discovered the magnetic effect of current.

Experiment

A compass needle is placed near a wire.

When current flows:

Compass needle deflects.

Conclusion

Electric current produces magnetic field.

🌟 Electromagnet

A temporary magnet produced by passing current through a coil wound around soft iron.

Construction

Soft iron core
Insulated copper wire
Battery

Working

Current passes through coil.

Soft iron becomes magnetized.

When current stops:

Magnetism disappears.

🌟 Factors Affecting Strength of Electromagnet

1. Number of Turns

More turns → Stronger magnet

2. Current

More current → Stronger magnet

3. Soft Iron Core

Increases magnetic strength.

🌟 Uses of Electromagnets

1. Electric Bell

School bells

Door bells

2. Scrap Cranes

Used to lift iron scrap.

3. Loudspeakers

4. Relays

🌟 Electric Bell ⭐ Board Favourite

Works on magnetic effect of current.

Parts

Electromagnet
Hammer
Gong
Spring
Contact Screw
Battery
Switch

Working

Step 1

Switch pressed.

Step 2

Current flows.

Step 3

Electromagnet formed.

Step 4

Hammer strikes gong.

Step 5

Circuit breaks.

Step 6

Hammer returns.

Step 7

Cycle repeats.

Bell rings continuously.

🌟 Difference Between Permanent Magnet and Electromagnet

Permanent Magnet	Electromagnet
Always magnetic	Temporary
Cannot be switched off	Can be switched off
Fixed strength	Adjustable strength
Less useful in machines	Widely used

🎯 PYQs (Previous Year Questions)

Q1. Why is fuse wire made of a material having low melting point?

Answer:

Fuse melts quickly when excess current flows and protects appliances.

Q2. State two applications of heating effect of current.

Answer:

Electric iron
Electric heater

Q3. What is an electromagnet?

Answer:

A temporary magnet produced by passing current through a coil wound around a soft iron core.

Q4. What is overloading?

Answer:

Drawing excessive current from a circuit is called overloading.

Q5. Why are MCBs preferred over fuses?

Answer:

MCBs are reusable, safer and operate automatically.

🔥 BOARD LEVEL MCQs

1. The heating element of an electric iron is made of:

A) Copper

B) Nichrome

C) Aluminium

D) Iron

✅ Answer: B

2. Which of the following has high resistance?

A) Nichrome

B) Silver

C) Copper

D) Gold

✅ Answer: A

3. Fuse wire has:

A) High melting point

B) Low melting point

C) Zero resistance

D) Infinite resistance

✅ Answer: B

4. MCB stands for:

A) Magnetic Circuit Board

B) Miniature Circuit Breaker

C) Main Current Breaker

D) Main Circuit Board

✅ Answer: B

5. Electromagnets are made using:

A) Copper core

B) Aluminium core

C) Soft iron core

D) Steel core

✅ Answer: C

6. Oersted discovered:

A) Heating effect

B) Magnetic effect

C) Chemical effect

D) Sound effect

✅ Answer: B

7. Which device works on magnetic effect?

A) Iron

B) Heater

C) Bell

D) Toaster

✅ Answer: C

8. Which phenomenon may cause fire hazards?

A) Magnetic effect

B) Heating effect

C) Short circuit

D) Reflection

✅ Answer: C

🔥 Assertion-Reason Questions

Q1

Assertion:

Fuse protects appliances.

Reason:

Fuse wire has low melting point.

A. Both true and Reason explains Assertion

B. Both true but Reason does not explain

C. Assertion true, Reason false

D. Assertion false, Reason true

✅ Answer: A

Q2

Assertion:

Electromagnets are temporary magnets.

Reason:

Their magnetism disappears when current stops.

✅ Answer: A

🎯 Case-Based Questions

Case Study

Rohan connected an electric bell to a battery. When he pressed the switch, the hammer repeatedly struck the gong and produced sound.

Q1. Which effect of current is involved?

A) Heating

B) Magnetic

C) Chemical

D) Optical

✅ Answer: B

Q2. Which component becomes magnetic?

A) Hammer

B) Gong

C) Electromagnet

D) Spring

✅ Answer: C

Q3. Why does hammer return back?

A) Gravity

B) Spring action

C) Battery

D) Wire

✅ Answer: B

📝 Practice Questions

Very Short Answer

Define heating effect of current.
Name the material used in heating elements.
What is a fuse?
Define electromagnet.
Who discovered magnetic effect of current?

Short Answer Questions

Explain working of fuse.
Explain overloading.
Explain short circuit.
Why is nichrome used in heaters?
Write uses of electromagnets.

Long Answer Questions

Explain working of electric bell with diagram.
Explain construction and working of electromagnet.
Differentiate between fuse and MCB.
Explain Oersted's experiment.

⭐ NCERT Important Points for Boards

✔ Nichrome is used in heating elements.

✔ Fuse protects appliances from excessive current.

✔ MCB is safer than fuse.

✔ Oersted discovered magnetic effect of current.

✔ Electric bell works on magnetic effect.

✔ Electromagnets are temporary magnets.

✔ Soft iron is used in electromagnets.

✔ Overloading and short circuit may cause fire hazards.