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How can the electric current in a circuit be kept continuous?

1. What is Current?
2. How can electric current in a circuit be kept continuous?

Ans:

The word current means flow.

Electric Current refers to charges in motion. The most common way of producing current is by applying a potential difference across the terminals of a conductor. Then the free electrons in the conductor drifts towards the positive terminal.

The current in the circuit can be kept continuous by providing a constant potential difference between two points of the circuit. This is usually done by connecting the ends of the circuit to the terminals of an electrochemical cell (which converts chemical energy to electrical energy) or a dynamo (which converts mechanical energy to electrical energy)

Devices using permanent magnets and electromagnets

1. List the devices where permanent magnets & electromagnets are used.
2. Sketch the pattern of the field lines around a current carrying:
• Straight Conductor

• Loop of wire

• Solenoid

Ans:

1. Permanent Magnets are used in
• Laboratory magnets
• loud speakers
• microphones
• cyclotron
• generators
• and many more
2. Pattern of the field lines around a current carrying

Straight Conductor

Loop of wire

Solenoid

A Question from Magnetic Effects of Current

“A current carrying wire is placed above a magnetic needle. What do you observe? If you want to increase this effect, what will you do? If you want to reverse the effect, what will you do?”

Ans: When a current carrying conductor is placed above a magnetic needle, the magnetic needle is deflected and tends to align itself perpendicular to the conductor. The effect can be increased by increasing the strength of current through the wire or by decreasing the distance.

However, the maximum deflection which can be produced is 90 degree, when the magnetic field produced by the current carrying wire is very much greater than the earth’s magnetic field.

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