State the differences between magnetic field and magnetic field line.

Magnetic Field Magnetic field line The magnetic field is the region surrounding a magnet, in which the force of the magnet can be detected. Magnetic field lines or lines of force are the imaginary lines used to visualise magnetic field. The magnetic field is a quantity that has both direction and magnitude. It is a vector quantity. The magnetic field lines always begin from the N-pole of a magnet and end on the S-pole of the magnet. The magnetic field is created by an electric current or magnetic dipole and the field imparts magnetic forces on other particles that are in it. The magnetic field lines are the path along which an isolated unit north pole would move along in the field.

How can the power of an electric motor be increased? Explain with any three points.

An electric motor is a rotating device that converts electrical energy to mechanical energy. Electric motor is used as an important component in electric fans, refrigerators, mixers, washing machines, computers, etc. (i) an electromagnet in place of permanent magnet, (ii) large number of turns of the conducting wire in the current carrying coil, (iii) a soft iron core on which the coil is wound. The soft iron core, on which the coil is wound, plus the coils, is called an armature. This enhances the power of the motor.

State the differences between electromagnet and permanent magnet. (Give any three points).

Electromagnets Permanent magnets An electromagnet is made from a coil of wire which acts as a magnet when an electric current passes through it. Often an electromagnet is wrapped around a core of ferromagnetic material like steel, which enhances the magnetic field produced by the coil A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. As the name suggests, a permanent magnet is permanent. This means that it always has a magnetic field and will display a magnetic behaviour at all times. An electromagnetic magnet only displays magnetic properties when an electric current is applied to it. Permanent magnets magnetic properties exist when the magnet is magnetized. The strength of an electromagnet can be adjusted by the amount of electric current allowed to flow into it. As a result, the same electromagnet can be adjusted for different strength levels. Permanent magnet strength depends upon the material used in its creation.

What is an electromagnet? Draw a circuit diagram to show how a soft iron piece can be transformed into an electromagnet.

The magnetic field produced due to current flowing in a coil or a solenoid can be used to magnetise a material like soft iron temporarily. The insulated copper wire is wrapped on a soft iron piece. When current is passed through the coil using a battery and a key the iron piece behaves like a bar magnet as long as the current is being passed. Such a magnet is called an electromagnet. A strong magnetic field produced inside a solenoid can be used to magnetise a piece of magnetic material, like soft iron, when placed inside the coil as shown in the figure.

Distinguish between the terms ‘overloading’ and ‘short-circuiting’ as used in domestic circuits.

Overloading Short-circuiting Overloading occurs when an electric circuit draws more current than the permitted value. Short-circuiting occurs when the ends of a circuit are connected by a conductor of negligible resistance. To avoid overloading, too many appliances should not be connected and devices that draw a lot of currents should be avoided. To avoid short-circuiting, care should be taken while connecting the wires and the wires should not be left open.

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 13 - Magnetic Effects of Electric Current>meghalaya-2018>Q 5

EASY

10th Meghalaya Board

IMPORTANT

Earn 100

What is earthing? Why is earthing of electrical appliances necessary?

Important Questions on Magnetic Effects of Electric Current

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10th Meghalaya Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 13 - Magnetic Effects of Electric Current>meghalaya-2019>Q 6

According to the new convention, the colour of insulation for live wire is

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IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 13 - Magnetic Effects of Electric Current>meghalaya-2019>Q 7

The strength of magnetic field

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IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 13 - Magnetic Effects of Electric Current>meghalaya-2019>Q 8

What is an electromagnet? State it's one of practical use.

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10th Meghalaya Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 13 - Magnetic Effects of Electric Current>meghalaya-2019>Q 9

What is a solenoid? Can you determine the North and South poles of a current-carrying solenoid with the help of a bar magnet? Explain.

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IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 13 - Magnetic Effects of Electric Current>meghalaya-2019>Q 10

If a single coil of large number of turns is used in a motor, it is found that the motion of the coil is not smooth but jerky.
Why is it so? How can this jerky motion be converted into a smooth circular motion?

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 13 - Magnetic Effects of Electric Current>meghalaya-2020>Q 11

An electric device which converts electric energy into mechanical energy is called

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IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 13 - Magnetic Effects of Electric Current>meghalaya-2020>Q 12

Why is fuse wire always placed in a live circuit?

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