Electric Current &Heating Effect
of Electric Current
Grade 7 – Simple, Clear & Conceptual
Understanding
2.
What is ElectricCurrent?
• Electric current is the flow of electric charges.
• In metals, free electrons move and create
current.
• Movement of electrons is called electric
current.
3.
Electrons – TinyWorkers
• Everything is made of atoms.
• Atoms contain electrons.
• Some electrons in metals are free to move.
4.
Why Do ElectronsMove? (Voltage)
• Electrons need a push to move.
• This push is called voltage.
• Battery provides voltage.
5.
What is anElectric Circuit?
• An electric circuit is a closed path.
• Electric current flows only in a closed circuit.
• If the circuit is open, current stops.
6.
Components of anElectric Circuit
• Battery – source of electrical energy.
• Wires – path for current.
• Switch – controls the flow of current.
• Device – uses electrical energy.
7.
Resistor – FriendlyIdea
• Controls the flow of electric current.
• Acts like a speed breaker for electrons.
• Protects devices from damage.
8.
Capacitor – SimpleMeaning
• Stores electric charge temporarily.
• Releases energy when needed.
• Acts like a small electricity tank.
9.
Measuring Instruments
• Ammeter– measures electric current
(Ampere).
• Voltmeter – measures voltage (Volt).
• Ammeter in series, voltmeter in parallel.
10.
Conductor and Insulator
•Conductor allows current to flow (Copper).
• Insulator blocks current (Wood, Plastic).
• Current flows only where electrons are free.
11.
Heating Effect ofElectric Current
• Heat is produced when current flows through
a conductor.
• This is called heating effect of electric current.
• Heating occurs due to resistance of the
conductor.
12.
Electric Lamp (FilamentBulb)
• Uses a thin tungsten filament.
• Filament has very high melting point.
• Filament glows due to heating effect.
13.
Compact Fluorescent Lamp(CFL)
• Does not use heating effect to produce light.
• Electric current excites mercury vapour.
• UV rays are converted into visible light by
phosphor coating.
14.
Electric Fuse
• Asafety device used in electric circuits.
• Made of a thin wire with low melting point.
• Melts and breaks circuit during excess current.
15.
Miniature Circuit Breaker(MCB)
• An automatic protective switch.
• Trips during excess current or short circuit.
• Can be reset after tripping.
16.
Reasons for ExcessCurrent in a
Circuit
• Overloading of the circuit.
• Short circuit due to damaged insulation.
• Using too many appliances at one time.
17.
Applications of HeatingEffect of
Current
• Electric iron
• Electric heater
• Electric kettle
• Toaster
• Geyser
• Electric fuse
18.
Factors Affecting HeatingEffect
• Amount of current flowing.
• Resistance of the conductor.
• Time for which current flows.
19.
Golden Summary
• Electriccurrent is flow of electrons.
• Heating effect is caused by resistance.
• Fuses and MCBs protect circuits.
• Modern lighting saves energy.
