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# NCERT Solutions for Class 10th Science

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## Chapter 13. Magnetic Effects of Electric Current

### Additional Questions With Solutions

Chapter-13. Magnetic Effects of Electric Current

Que. – By which name the natural magnate is known?

Ans. – Magnetite.

Que. – What is magnetic

Que. – What is solonoide ?

Ans. – A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is called a solenoid.

Que . – On which basis MRI does work to get images from the various organs of the human body?

Ans. – MRI method works basis on magnetic field presence in the body to get images from the various organs of the human body.

Que. – From where do magnetic fields produce in the human body?

Ans. - Magnetic fields produce in the human body from flowing ionic current in nervous cells of our body.

Que. – Name the parts of human body which produce magnetic field?

Ans. – The heart and The brain.

Que. – Name the device in which converts electric energy into mechanical energy?

Ans. – Electric Motor.

Que. – What is the function of split ring in electric motor?

Ans. -   split ring acts as commutator in electric motor.

Que. – What happens to the magnetic field around a straight conductor, when current is passed through it? The conditions are as following:

1. Increasing electric current.
2. Placing the compass at the farther point from the conducting wire.
3. Size of concentric circles, which represent the magnetic field.

Ans. –

1. Produced magnetic field increases.
2. Deflection in the needle decreases.
3.  Size of concentric circles, which represent the magnetic field, becomes larger and larger.

Que. – Name a special kind of technology of medical science in which makes base to magnetic field to get images of organs?

Ans. – MRI.

Que. – What is commutator?

Ans. – A device that reverses the direction of flow of current through a circuit is called a commutator.

Que. – A straight conductor produces magnetic field around it. Describe rule to find the direction of such a produced magnetic field by it.

Ans. – This rule is known as the right hand thumb rule. This rule is also known as Maxwell’s corkscrew rule. You are holding a current carrying straight conductor in your hand such that the thumb point towards the direction of current. Then your finger will wrap around the conductor in the direction of the field lines of the magnetic field.

Que. – There is another wire in domestic electric circuit instead of live wire and neutral wire, which has green insulated wire.

1. Name this wire.
2. What is the advantage of using this wire in domestic circuit?
3. Where does another end of this wire is connected instead of domestic circuit and how?

Ans. –

1. The earth wire.
2. It is used as a safety measure to ensure that any leakage of current to a metallic body does not give any severe electric shock to a user.
3. The other end of this wire is connected to a metallic body deep inside earth.

Que. – What is the potential different between live wire and neutral wire?

Ans – 220 V.

Que. – At what volt do we receive AC electric power in our houses and what is its frequency?

Ans. -   we receive AC electric power At 220 V and its frequency is 50 Hz.

Que. – Give the answers of the following questions.

1. What is the electromagnetic induction?
2. Who discovered the electromagnetic induction?
3. Write two processes to induce current in a coil.
4. Which process of both is more convenient to induce current in a coil?

Ans. –

1. The process by which a changing magnetic field in a conductor induces a current in another conductor. This process is called the electromagnetic induction.
2. Michael Faraday.
3.  (a)  Moving the coil in a magnetic field.

(b)  By changing the magnetic field around the coil.

1. Moving the coil in a magnetic field is move convenient to induce current in a coil.

Que.- What are the two methods of producing magnetic field? Which of these is better and why?

Ans. –

Que. – Give the answers of following question.

1. What do you understand by magnetic field?
2. Are there magnetic field lines inside the magnet? If yes, then explain, what is their direction?
3. Magnetic field is Vector or scalar? How?
4. Write three properties of magnetic field.

Ans. –

1. The region surrounding a magnet, in which the force of the magnet can be detected, is said to have a magnetic field.
2. Yes, there are magnetic field lines inside the magnet. The field lines emerge from North Pole and merge at the South Pole inside the magnet.
3. Magnetic field is Sadish Rashi, As It has both direction and magnitude.
4. Properties of magnetic field as follow:
1. The direction of field lines is from its south pole and to its north pole.
2. The magnetic field lines are closed curve.
3.  It has both direction and magnitude.

Que. – How will you identify the relative strength (severity) of magnetic field?

Ans. – the relative strength (severity) of magnetic field is shown by the degree of closeness of the field lines. Where the magnetic field lines are crowded, magnetic field is stronger there.

Que. – A bar magnet “A” whose magnetic field lines are very closer, while another bar magnet “B” magnetic field lines are farther than “A”. “A” is brought near “B”. Which magnet works stronger, why?

Ans. - Bar magnet “A”. As where the magnetic field lines are crowded, magnetic field is stronger there and that magnet works stronger.

Que. – How much powerful will be the magnetic field produced by a circular coil having n turns than produced by the single turn?

Ans. – n times as larger as that produced by single turn.

Q2. What is the difference between an electromagnet and a permanent magnet?

Ans2.

 Electromagnet Permanent magnet 1. The magnetic field produced is generally very strong. 2. The strength of the magnetic-field can be controlled by controlling various factors such as the current and the number of turns in the solenoid. 3. The polarity of the magnet can be changed by reversing the direction of current. 4. Normally soft iron is used for making electro magnets. 1. Generally the magnetic field produced is low and moderate. 2. The strength of the magnetic-field of a permanent magnet is permanent but changes (decreases) with the temperature. 3. The polarity of the magnet can not be changed. 4. Cobalt, steel etc., are used for the purpose.

Q3. What is the usual colour code followed for connecting live, neutral and earth wires? Why is it so important?

Ans3. The old convention is red for live, black for neutral and green for earth. The internationally accepted convention is brown for live, light blue for neutral and green or yellow for earth.
The selection of earth wire is made in such a way that it can withstand stronger currents. The thickness of other wires depends upon the power rating of the appliance.
The distinction between the colours is necessary because the wires are taken according to their current carrying capacities.

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