Electricity powers our homes, industries, schools, and even our hearts (through electrical impulses!).
But electricity is more than just light bulbs and fans — it can produce heat, light, and magnetism.
In this chapter, we’ll explore:
By the end, you’ll not only understand the science behind circuits but also how electricity shapes our daily life — from the switch in your home to trains running on electromagnets!
| Competency | Learning Outcome | NEP Skill |
|---|---|---|
| Conceptual Understanding | Explain heating and magnetic effects of current | Conceptual Clarity |
| Inquiry & Investigation | Observe current flow & experiment with electromagnets | Scientific Temper |
| Application | Relate electrical concepts to daily life | Practical Learning |
| Analytical | Understand safety devices and their role | Critical Thinking |
| Ethical Awareness | Use electricity responsibly & conserve energy | Sustainability |
Electric current is the flow of electrons through a conductor (like a copper wire).
It always flows from the positive terminal to the negative terminal of a cell in a circuit diagram.
| Symbol | Component | Function |
|---|---|---|
| 🔋 | Cell | Source of electric energy |
| ⚡ | Battery | Combination of cells |
| 💡 | Bulb | Converts electric energy to light & heat |
| 📏 | Wire | Conducts current |
| 🔘 | Switch | Opens or closes the circuit |
Aim: To test if a circuit is complete.
Materials: Cell, wire, and bulb.
Process: Connect wires from the cell to the bulb.
Observation: The bulb glows only when the circuit is closed, showing current flow.
⚡ A closed circuit = flow of electricity. An open circuit = no current.
When an electric current passes through a wire, it gets hot.
This is called the heating effect of electric current.
The heating happens because electrons collide with atoms in the wire, transferring energy as heat.
H=I2RtH = I^2 R tH=I2Rt
where,
H = Heat produced
I = Current (in Amperes)
R = Resistance (in Ohms)
t = Time (in seconds)
So, more current = more heat.
| Device | Purpose | Explanation |
|---|---|---|
| Electric Iron | Iron clothes | Coil gets heated |
| Geyser | Heat water | Converts electricity to heat |
| Toaster | Bake bread | Heating element glows red |
| Bulb (filament type) | Light | Tungsten filament heats & emits light |
Aim: Observe heating effect.
Procedure:
Conclusion:
Thinner and longer wires heat up faster due to higher resistance.
When current exceeds a safe limit, wires can overheat and cause fires.
A fuse protects electrical circuits by melting and breaking the circuit when excess current flows.
| Component | Material | Function |
|---|---|---|
| Fuse wire | Tin + Lead | Melts easily when overheated |
| Circuit breaker | Automatic switch | Replaces traditional fuse |
🧠 Fuse acts like a bodyguard — it sacrifices itself to save the circuit.
Discovered by Hans Christian Ørsted (1820), who noticed that a current-carrying wire deflects a nearby compass needle.
This proved that electric current produces a magnetic field.
Materials: Battery, wire, compass.
Steps:
Inference:
Electric current can act like a magnet — this is the magnetic effect of electric current.
If you hold the wire with your right hand, thumb pointing in current’s direction,
then the curl of fingers shows the direction of the magnetic field.
🌀 Field lines form concentric circles around the wire.
When current passes through a circular loop, magnetic field lines become stronger at the center.
Winding several loops forms a solenoid, which behaves like a bar magnet.
An electromagnet is a temporary magnet made by passing current through a coil around a soft iron core.
Aim: To make a simple electromagnet.
Materials: Iron nail, wire, battery.
Process:
Observation:
Magnetism appears when current flows and disappears when stopped.
🔁 Reversible magnetism = electromagnetism.
| Device | Use |
|---|---|
| Electric Bell | Produces sound by magnetizing and demagnetizing an iron hammer |
| Electric Motor | Converts electrical energy to mechanical energy |
| Cranes | Lifting heavy iron scrap |
| MRI Machines | Imaging body organs using magnetic fields |
An electric bell is an application of electromagnetism.
Components:
Iron hammer, electromagnet, armature, contact screw, gong, switch.
Working:
An electric motor converts electrical energy → mechanical energy.
It works on the magnetic effect of current.
When a current-carrying coil is placed in a magnetic field, it experiences a force that causes it to rotate.
Applications:
💡 Motors turn electricity into motion – one of the most powerful human inventions.
✅ Never touch switches or wires with wet hands
✅ Use insulated tools
✅ Switch off unused devices
✅ Replace damaged plugs & wires
✅ Use proper fuse rating
💡 Use LED bulbs instead of filament bulbs.
🌞 Use natural light during day.
🧺 Switch off appliances when not in use.
♻️ Promote renewable energy (solar, wind, hydro).
“Energy saved = Energy produced.”
| Domain | Skill | Example Activity |
|---|---|---|
| Conceptual | Understand electricity & magnetism link | Compass and circuit activity |
| Analytical | Apply Joule’s Law | Calculate heat in a circuit |
| Practical | Construct electromagnet | Lab demonstration |
| Creative | Build working model | Mini electric bell project |
| Ethical | Save energy responsibly | Energy audit at home |
🔹 Electric current = flow of electrons
🔹 Heating effect = current produces heat (H = I²Rt)
🔹 Magnetic effect = current produces magnetic field
🔹 Electromagnet = temporary magnet using current
🔹 Electric bell = electromagnet + hammer
🔹 Motor = converts electricity to motion
📍 Define: Electromagnet, Heating Effect, Fuse
📍 Differentiate: Magnetic vs Heating Effects
📍 Explain: Working of electric bell
📍 Formula: Joule’s Law of Heating
📍 Value Question: Why should we save electricity?
✅ Electric current causes heat and magnetism
✅ Heat depends on current, resistance, and time
✅ Magnetic field forms around current-carrying wires
✅ Electromagnets are used in bells & cranes
✅ Electric motors convert electricity into movement
✅ Conserve electricity for a sustainable future 🌱
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