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Relay
A relay is an electrically operated switch. Coil current creates a magnetic field that moves an armature and changes contacts, often isolating control and load circuits.
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Relay
A relay is a switch that can be operated by electricity instead of by your hand.
Recommended for Class 10
Relay
A relay is an electrically operated switch.
In a traditional electromagnetic relay, current through a coil produces a magnetic field. This magnetic effect moves an armature and changes electrical contacts.
A relay therefore allows one electrical circuit to control the switching of another circuit.
Main Parts
A basic electromagnetic relay contains:
coil/electromagnet; armature; contacts; spring or return mechanism.
Why Relays Are Useful
A relatively small control current can operate contacts controlling another circuit.
The control circuit and switched circuit can also be electrically isolated in many relay arrangements.
Applications
Relays are used in:
automatic control systems; alarms; switching circuits; protection/control equipment.
Relay — Advanced
An electromagnetic relay converts a control current into magnetic force that mechanically changes contact states, often providing galvanic isolation between control and load circuits.
Common Mistakes
Common Mistakes
- Mistake
Mistake: A relay is the same component as a transistor. Correction: Both can be used for switching, but a traditional relay uses mechanically moving contacts.
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
Relay → electrically operated switch.
Coil → magnetic field.
Armature → moves.
Contacts → open/close circuit.
- Definition
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Practice
PQ
Q1. Define relay.
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Q2. Role of coil.
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Q3. Armature.
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Q4. Contacts.
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Q5. One application.
Exam Practice
EQ
Q1. Explain electromagnetic relay operation.
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Q2. Name main relay parts.
EQ
Q3. Explain how a small control circuit switches another circuit.
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Q4. Give applications.
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Q5. Compare relay and transistor switching conceptually.
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.