Class 10 > Unit # 15: Current Electricity > Electrical Components

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Electrical Components and Their Uses

Q.7 Define Electrical components and their uses.

"Electrical components are fundamental physical devices or building blocks used in an electrical or electronic circuit to control, direct, or modify electric current, voltage, and energy."

Below is a detailed overview of essential electrical components, their working principles, uses, and visual schematic representations:

1. Switches or Keys

Definition & Use: One of the most fundamental electrical components used to turn electric circuits ON and OFF. When pressed or flipped, it opens or closes the path, allowing or interrupting the flow of electric current.

Fig: Schematic representation of an open electrical switch.

2. Resistor

Definition & Use: A two-terminal electrical component designed to implement electrical resistance ($R$) as a circuit element. It restricts current flow, divides voltages, and protects sensitive components.

Fig: Fixed resistor schematic symbol.

3. Battery

Definition & Use: An electrical source that stores chemical energy and converts it into electrical energy to maintain a continuous potential difference across a circuit.

Fig: Multi-cell battery symbol showing positive and negative terminals.

4. Transducers

Definition & Use: An electrical component that converts one form of energy into another form of energy. For example, a microphone converts sound energy into electrical audio signals.

Fig: General block representation of an energy transducer.

5. LDRs (Light Dependent Resistors)

Definition & Use: A photoresistor or light-sensitive electronic component whose resistance varies with incident light intensity. Widely used in automatic security lights and twilight switches.

• (i) In low light levels: The resistance of an LDR is high, allowing very little current to flow.
• (ii) In bright light: The resistance of an LDR is low, allowing more current to flow.

Fig: Light Dependent Resistor (LDR) schematic symbol with incoming light arrows.

6. Thermistors

Definition & Use: Thermally sensitive resistors whose resistance strongly depends on temperature. They are extensively used to measure and monitor temperature very accurately in digital thermometers and thermostats.

Fig: Thermistor schematic symbol with temperature coefficient indicator.

7. Relay

Definition & Use: An electrically operated switch that uses an electromagnet to mechanically or electronically switch heavy-duty electrical circuits ON and OFF using a low-power control signal.

Fig: Electromagnetic relay coil control symbol.

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