How a Doorbell Works : āĻĻā§°ā§āĻāĻžā§° āĻāĻŖā§āĻāĻž āĻā§āĻ¨ā§āĻā§ āĻāĻžāĻŽ āĻā§°ā§
Main Parts (āĻŽā§āĻ˛ āĻ āĻāĻļāĻ¸āĻŽā§āĻš)
- Doorbell Switch : āĻĻā§°ā§āĻāĻžā§° āĻ¸ā§āĻāĻ
- Electromagnet (Coil) : āĻāĻ˛ā§āĻā§āĻā§ā§°’āĻŽā§āĻāĻ¨ā§āĻ (āĻāĻāĻ˛)
- Striker (Hammer) : āĻāĻāĻžāĻ¤āĻāĻžā§°ā§ (āĻšā§āĻŽāĻžā§°)
- Electrical Wires : āĻŦā§āĻĻā§āĻ¯ā§āĻ¤āĻŋāĻ āĻ¤āĻžā§°
- Bell Plate : āĻāĻŖā§āĻāĻžā§° āĻĒā§āĻ˛ā§āĻ
- Power Source : āĻļāĻā§āĻ¤āĻŋā§° āĻā§āĻ¸
Working Steps (āĻāĻžāĻŽ āĻā§°āĻžā§° āĻ§āĻžāĻĒāĻ¸āĻŽā§āĻš)
- User presses the doorbell switch : āĻŦā§āĻ¯ā§ąāĻšāĻžā§°āĻāĻžā§°ā§āĻ¯āĻŧā§ āĻĻā§°ā§āĻāĻžā§° āĻ¸ā§āĻāĻ āĻāĻŋāĻĒā§
- Circuit becomes complete : āĻāĻžā§°ā§āĻāĻŋāĻ āĻ¸āĻŽā§āĻĒā§ā§°ā§āĻŖ āĻšāĻ¯āĻŧ
- Current flows through the coil : āĻāĻāĻ˛āĻ¤ āĻŦāĻŋāĻĻā§āĻ¯ā§ā§ āĻĒā§ā§°āĻŦāĻžāĻš āĻšāĻ¯āĻŧ
- Electromagnet pulls the striker : āĻāĻ˛ā§āĻā§āĻā§ā§°’āĻŽā§āĻāĻ¨ā§āĻā§ āĻšā§āĻŽāĻžā§° āĻāĻžāĻ¨ā§
- Striker hits the bell plate : āĻšā§āĻŽāĻžā§°ā§ āĻāĻŖā§āĻāĻžā§° āĻĒā§āĻ˛ā§āĻāĻ¤ āĻāĻāĻžāĻ¤ āĻā§°ā§
- Sound is produced : āĻļāĻŦā§āĻĻ āĻā§āĻĒāĻ¨ā§āĻ¨ āĻšāĻ¯āĻŧ
Switch Condition (āĻ¸ā§āĻāĻā§° āĻ ā§ąāĻ¸ā§āĻĨāĻž)
- Switch open → No current → No sound : āĻ¸ā§āĻāĻ āĻā§āĻ˛āĻž → āĻŦāĻŋāĻĻā§āĻ¯ā§ā§ āĻ¨āĻžāĻ → āĻļāĻŦā§āĻĻ āĻ¨āĻžāĻ
- Switch pressed → Current flows → Bell rings : āĻ¸ā§āĻāĻ āĻāĻŋāĻĒāĻž → āĻŦāĻŋāĻĻā§āĻ¯ā§ā§ āĻĒā§ā§°āĻŦāĻžāĻš → āĻāĻŖā§āĻāĻž āĻŦāĻžāĻā§
Important Concept (āĻā§ā§°ā§āĻ¤ā§āĻŦāĻĒā§āĻ°ā§āĻŖ āĻ§āĻžā§°āĻŖāĻž)
Electromagnets convert electrical energy into mechanical motion, which produces sound.
āĻāĻ˛ā§āĻā§āĻā§ā§°’āĻŽā§āĻāĻ¨ā§āĻā§ āĻŦāĻŋāĻĻā§āĻ¯ā§ā§ āĻļāĻā§āĻ¤āĻŋāĻ āĻ¯āĻžāĻ¨ā§āĻ¤ā§ā§°āĻŋāĻ āĻāĻ¤āĻŋāĻ¤ ā§°ā§āĻĒāĻžāĻ¨ā§āĻ¤ā§° āĻā§°ā§, āĻ¯āĻžā§° āĻĢāĻ˛āĻ¤ āĻļāĻŦā§āĻĻ āĻā§āĻĒāĻ¨ā§āĻ¨ āĻšāĻ¯āĻŧāĨ¤
Revision :āĻĒā§āĻ¨ā§°āĻžāĻŦā§āĻ¤ā§āĻ¤āĻŋ
- Press switch → Current flows
- Electromagnet works
- Striker hits bell
- Sound produced
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MCQ
Q1. What type of device is used in an electric doorbell ? āĻĒā§ā§°āĻļā§āĻ¨: āĻŦā§āĻĻā§āĻ¯ā§āĻ¤āĻŋāĻ āĻĻā§°ā§āĻāĻžā§° āĻāĻŖā§āĻāĻžāĻ¤ āĻā§āĻ¨ āĻ§ā§°āĻŖā§° āĻ¯āĻ¨ā§āĻ¤ā§ā§° āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻšāĻ¯āĻŧ ?
Options: (a) Motor (b) Generator (c) Electromagnet (d) Battery
Ans: (c) Electromagnet
Explanation: Doorbells use an electromagnet to move the striker. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻĻā§°ā§āĻāĻžā§° āĻāĻŖā§āĻāĻžāĻ¤ āĻāĻ˛ā§āĻā§āĻā§ā§°’āĻŽā§āĻāĻ¨ā§āĻ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻšāĻ¯āĻŧāĨ¤
Q2. When the switch is pressed, what happens first ? āĻĒā§ā§°āĻļā§āĻ¨: āĻ¸ā§āĻāĻ āĻāĻŋāĻĒāĻŋāĻ˛ā§ āĻĒā§ā§°āĻĨāĻŽā§ āĻāĻŋ āĻāĻā§ ?
Options: (a) Sound produced (b) Circuit breaks (c) Circuit completes (d) Bell stops
Ans: (c) Circuit completes
Explanation: Pressing the switch completes the circuit. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻ¸ā§āĻāĻ āĻāĻŋāĻĒāĻŋāĻ˛ā§ āĻāĻžā§°ā§āĻāĻŋāĻ āĻ¸āĻŽā§āĻĒā§ā§°ā§āĻŖ āĻšāĻ¯āĻŧāĨ¤
Q3. The striker in a doorbell is also called ? āĻĒā§ā§°āĻļā§āĻ¨: āĻĻā§°ā§āĻāĻžā§° āĻāĻŖā§āĻāĻžāĻ¤ striker āĻāĻžāĻ āĻā§ā§ąāĻž āĻšāĻ¯āĻŧ ?
Options: (a) Coil (b) Hammer (c) Plate (d) Wire
Ans: (b) Hammer
Explanation: Striker is the hammer that hits the bell. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: Striker āĻšā§āĻā§ āĻšā§āĻŽāĻžā§° āĻ¯āĻŋ āĻāĻŖā§āĻāĻžāĻ¤ āĻāĻāĻžāĻ¤ āĻā§°ā§āĨ¤
Q4. What is the function of the coil in a doorbell ? āĻĒā§ā§°āĻļā§āĻ¨: āĻĻā§°ā§āĻāĻžā§° āĻāĻŖā§āĻāĻžāĻ¤ āĻāĻāĻ˛ā§° āĻāĻžāĻŽ āĻāĻŋ ?
Options: (a) Produce light (b) Act as electromagnet (c) Store charge (d) Stop current
Ans: (b) Act as electromagnet
Explanation: The coil becomes an electromagnet when current flows. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻŦāĻŋāĻĻā§āĻ¯ā§ā§ āĻĒā§ā§°āĻŦāĻžāĻš āĻš’āĻ˛ā§ āĻāĻāĻ˛ āĻāĻ˛ā§āĻā§āĻā§ā§°’āĻŽā§āĻāĻ¨ā§āĻ āĻšāĻ¯āĻŧāĨ¤
Q5. What happens when the switch is open ? āĻĒā§ā§°āĻļā§āĻ¨: āĻ¸ā§āĻāĻ āĻā§āĻ˛āĻž āĻĨāĻžāĻāĻŋāĻ˛ā§ āĻāĻŋ āĻšāĻ¯āĻŧ ?
Options: (a) Current flows (b) Sound produced (c) No current flows (d) Bell rings
Ans: (c) No current flows
Explanation: Open circuit means no current, so no sound. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻāĻžā§°ā§āĻāĻŋāĻ āĻā§āĻ˛āĻž āĻĨāĻžāĻāĻŋāĻ˛ā§ āĻŦāĻŋāĻĻā§āĻ¯ā§ā§ āĻ¨āĻžāĻĨāĻžāĻā§āĨ¤
Q6. What energy conversion occurs in a doorbell ? āĻĒā§ā§°āĻļā§āĻ¨: āĻĻā§°ā§āĻāĻžā§° āĻāĻŖā§āĻāĻžāĻ¤ āĻā§āĻ¨ āĻļāĻā§āĻ¤āĻŋ ā§°ā§āĻĒāĻžāĻ¨ā§āĻ¤ā§° āĻšāĻ¯āĻŧ ?
Options: (a) Mechanical → Electrical (b) Electrical → Mechanical (c) Chemical → Light (d) Heat → Sound
Ans: (b) Electrical → Mechanical
Explanation: Electrical energy is converted into mechanical motion. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻŦāĻŋāĻĻā§āĻ¯ā§ā§ āĻļāĻā§āĻ¤āĻŋ āĻ¯āĻžāĻ¨ā§āĻ¤ā§ā§°āĻŋāĻ āĻāĻ¤āĻŋāĻ¤ āĻĒā§°āĻŋāĻŖāĻ¤ āĻšāĻ¯āĻŧāĨ¤
Q7. Which part produces sound in a doorbell ? āĻĒā§ā§°āĻļā§āĻ¨: āĻĻā§°ā§āĻāĻžā§° āĻāĻŖā§āĻāĻžāĻ¤ āĻļāĻŦā§āĻĻ āĻā§āĻ¨ āĻ āĻāĻļā§ āĻā§āĻĒāĻ¨ā§āĻ¨ āĻā§°ā§ ?
Options: (a) Wire (b) Coil (c) Bell plate (d) Battery
Ans: (c) Bell plate
Explanation: Sound is produced when striker hits the bell plate. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻšā§āĻŽāĻžā§°ā§ āĻĒā§āĻ˛ā§āĻāĻ¤ āĻāĻāĻžāĻ¤ āĻā§°āĻŋāĻ˛ā§ āĻļāĻŦā§āĻĻ āĻšāĻ¯āĻŧāĨ¤
Q8. What is the role of the power source ? āĻĒā§ā§°āĻļā§āĻ¨: āĻļāĻā§āĻ¤āĻŋā§° āĻā§āĻ¸ā§° āĻāĻžāĻŽ āĻāĻŋ ?
Options: (a) Produce sound (b) Supply current (c) Break circuit (d) Move striker
Ans: (b) Supply current
Explanation: Power source provides electrical energy. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻļāĻā§āĻ¤āĻŋā§° āĻā§āĻ¸ā§ āĻŦāĻŋāĻĻā§āĻ¯ā§ā§ āĻĒā§ā§°āĻĻāĻžāĻ¨ āĻā§°ā§āĨ¤
Q9. Why does the striker move ? āĻĒā§ā§°āĻļā§āĻ¨: striker āĻāĻŋāĻ¯āĻŧ āĻāĻ¤āĻŋ āĻā§°ā§ ?
Options: (a) Due to gravity (b) Due to electromagnet (c) Due to heat (d) Due to air
Ans: (b) Due to electromagnet
Explanation: Electromagnet attracts the striker. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻāĻ˛ā§āĻā§āĻā§ā§°’āĻŽā§āĻāĻ¨ā§āĻā§ striker āĻāĻžāĻ¨ā§āĨ¤
Q10. What completes the circuit in a doorbell ? āĻĒā§ā§°āĻļā§āĻ¨: āĻĻā§°ā§āĻāĻžā§° āĻāĻŖā§āĻāĻžāĻ¤ āĻāĻžā§°ā§āĻāĻŋāĻ āĻā§āĻ¨ā§āĻā§ āĻ¸āĻŽā§āĻĒā§ā§°ā§āĻŖ āĻšāĻ¯āĻŧ ?
Options: (a) Battery (b) Wire (c) Switch (d) Plate
Ans: (c) Switch
Explanation: Pressing the switch completes the circuit. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻ¸ā§āĻāĻ āĻāĻŋāĻĒāĻŋāĻ˛ā§ āĻāĻžā§°ā§āĻāĻŋāĻ āĻ¸āĻŽā§āĻĒā§ā§°ā§āĻŖ āĻšāĻ¯āĻŧāĨ¤
Revision (āĻĒā§āĻ¨ā§°āĻžāĻŦā§āĻ¤ā§āĻ¤āĻŋ)
- Switch → Circuit complete
- Coil → Electromagnet
- Striker → Hits bell
- Sound produced