Electric Current and Its Effects Class 7 Notes Science KEYWORDS and SUMMARY II Class 7 notes II NCERT based II

 1. Electric Current

Electric current is the flow of electric charges (electrons) through a conductor.

The source of electric current is a cell or battery.

The direction of current is taken from the positive to the negative terminal of the cell.

2. Electric Circuit

The path through which current flows is called an electric circuit.

It includes a cell, wires, switch, and bulb/device.

The circuit must be closed (complete) for current to flow.

If the circuit is open (broken), current stops.

3. Heating Effect of Electric Current

When an electric current passes through a conductor (wire), it gets heated up.

This is called the heating effect of current.

Examples: Electric heater, electric iron, bulb filament.

4. Factors Affecting the Heating Effect

Length and thickness of the wire (longer or thinner wire → more heat)

Amount of current (larger current → more heat)

5. Applications of Heating Effect

Used in electric iron, toaster, geyser, heater, and electric bulb.

The wire used for heating is called the heating element.

6. Electric Fuse

Fuse is a safety device that protects circuits from too much current (overloading).

It is a thin wire of low melting point connected in the circuit.

If current becomes too large, the fuse wire melts and breaks the circuit.

This prevents fire and damage to appliances.

Fuse wire melts when current increases because the heating effect becomes very large and its low melting point causes it to break.

7. Magnetic Effect of Electric Current

When electric current passes through a conductor, it produces a magnetic field around it.

This is called the magnetic effect of current.

8. Electromagnet

A coil of wire wound around a soft iron core and connected to a battery acts like a magnet.

This is called an electromagnet.

It works only when current flows.

Uses of Electromagnet:

Electric bell, crane to lift iron scrap, electric motors.

Electric Bell (Application of Electromagnet)

When switch is ON:

Current flows through coil → electromagnet forms.

It attracts the iron.

The hammer hits the gong → sound is produced.

The circuit breaks → electromagnet loses magnetism → armature goes back.

Circuit completes again → bell rings continuously.

Bell rings because the electromagnet attracts and releases the armature repeatedly, causing the hammer to strike the gong again and again.

KEYWORDS

1.Battery: A combination of two or more cells is called a battery. It is used in applications that require higher electricity, such as cars and toys.

2.Circuit diagram: A schematic diagram that represents an electric circuit using symbols for various electric circuit using standard symbols of the components used is called a Circuit diagram.

3.Electric components: Electric components are the different parts used in an electric circuit, such as a cell, bulb, switch, wires, and resistor, which help in the flow and control of electric current.

4.Electric bell: An electric bell is a device which produces sound. It consist of a coil on wire wound on an iron piece this coil act as Electromagnet.

5.Electromagnet: When an electric current flows through a wire, it behaves like a magnet. A current carrying coil of an insulated wire wrapped around a piece of iron is called an electromagnet.

6.Fuse: A fuse is a safety device that protects an electric circuit from harm. A small wire is inserted into insulating material to create it.

7.Heating effect of current: When electric current is passed though a wire it gets heated up. This is known as Heating effect of electric current. The amount of heat produced depends on its material, length and thickness.

8.Magnetic effect of current: When electric current is passed though a wire it behave as a magnet. This is known as Magnetic effect of electric current.