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प्रश्न
How is the working of an electric bell affected, if alternating current be used instead of direct current?
उत्तर
If an A.C. source is used in place of a battery, the core of the electromagnet will get magnetized, but the polarity at its ends will change. Since the attraction of the armature does not depend on the polarity of the electromagnet, the bell will still ring on pressing the switch.
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संबंधित प्रश्न
Name one device that uses an electromagnet.
Electromagnets are made up of :
The strength of the electromagnet can be increased by
How is an electromagnet made? Name two factors on which the strength of magnetic field of the electromagnet depends.
You are required to make an electromagnet from a soft iron bar by using a cell, an insulated coil of copper wire and a switch.
- Draw a circuit diagram to represent the process.
- Label the poles of the electromagnet.
A coil of insulated copper wire is wound around a piece of soft iron and current is passed in the coil from a battery. What name is given to the device so obtained? Give one use of the device mentioned by you.
Show with the aid of a diagram how a wire is wound on a U-shaped piece of soft iron in order to make it an electromagnet. Complete the circuit diagram and label the poles of the electromagnet.
State two ways through which the strength of an electromagnet can be increased.
Name one device that uses an electromagnet.
Why is soft iron used as the core of the electromagnet in an electric bell?
Name the material used for making the armature of an electric bell. Give a reason for your answer.
Explain, why steel is used in preference to soft iron for making permanent magnets while soft iron is used in preference to steel for making electromagnets.
What is an electroscope? Describe the different stages of charging a gold leaf electroscope negatively with the help of a diagram.
Explain in detail the application of electromagnets.
Assertion (A): When 2 long parallel wires, hanging freely are connected in parallel to a battery, they come closer to each other.
Reason (R): Wires carrying current in opposite directions repel each other.
Explain the working of the following device.
Speaker
Explain the working of the following device.
Magnetic levitation trains.
