Tag: current electricity and magnetism
Questions Related to current electricity and magnetism
Which of the following is a characteristic of a buzzer?
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It has different mechanism from electric bell.
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It has higher frequency of collision of gong and hammer
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It uses only AC power supply
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None of the above
In a buzzer, the simplest sort of doorbell, an electromagnet is used to operate a self-interrupting circuit. You can see how this system works in the diagram below. Click and hold the doorbell button to see how the buzzer works. ... This breaks the doorbell circuit, which shuts off the electromagnet.characteristic of a buzzer It has higher frequency of collision of gong and hammer
Which power supply can be used in electric bell
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$AC$
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$DC$
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Can't be predicted
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Both A and B
Electric bell works on the mechanism of electromagnets and for this any type of power either AC or DC can be used.
When the switch of an electric bell is pushed
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Flow of the current stops through the electromagnet in the bell
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Current starts to flow through the electromagnet
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Voltage decreases in the current flowing through the electromagnet
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Circuit is closed in the electric bell
When the switch of an electric bell is on then electric current in it :
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Flows and stops in succession
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Flows continuously
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First flows in one direction and after sometime in other direction
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Flows in beginning and then stops forever
The bell works on the principle of electromagnetism which says that when an electric current flows through the coil, the rods become magnetic and attract a piece of iron attached to a clapper. And the clapper hits the cap and comes back as the current stops, and hence the bell rings. So the current flows and stops in succession. And in this way the bell rings.
Why doorbell rings repeatedly when switch is pressed
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Because of nature of current
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Because electrical switch is built in such a manner
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Because of make and break arrangement
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Because of slight humidity in the circuit
Make and break arrangement causes striker to repeatedly hit the metal gong as long as switch is pressed. When Circuit is complete, electromagnet attracts the striker which hits metal gong. As soon as the striker moves, circuit breaks and electromagnet is inactive. Because of flexibility of striker, it moves back to its original position. As soon as it reaches original position, circuit is complete. This process repeats continuously.
What will happen if the strip in a doorbell loses its flexibility?
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Striker may break if current is large.
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After hitting the metal gong, it never returns to original position and only a single sound is produced.
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System of doorbell breaks
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Both A and B
Because of lack of flexibility, striker will resist change of motion more and may break if current is large.
What is the use of flexibility strip in a doorbell?
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It brings back striker to its original position
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It supports the motion of the striker
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It completes the electric circuit flexibly
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Its a safety precaution
Without the flexibility strip, the striker will not come back to original position when the electrical circuit breaks.
Electric doorbell
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Always consume power
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Consume power only when switch is pressed
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Do not consume power practically and needs only starting power
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cant say
When switch is pressed, circuit completes and ringing begins. Hence, electrical energy is converted to sound energy. As switch is released, no current flows and no energy is consumed,
Exposed Electric doorbell can be damaged by
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Mechanical damage
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High Electric currents
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Humidity
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All of the above
Mechanical Damage to metal gong or striker may hinder working of the bell.
During a doorbell ringing
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Current always flows in the circuit
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Electromagnet is always present
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Striker is always in contact with metal gong
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Striker always repeatedly hits metal gong
Striker repeatedly hits the metal gong when doorbell is ringing.
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