# Magnetic Effects of Electric Current Chapter 13 NCERT Textbook PDF

NCERT Solutions for Class 10 Science Chapter 13‘ PDF Quick download link is given at the bottom of this article. You can see the PDF demo, size of the PDF, page numbers, and direct download Free PDF of ‘Ncert Class 10 Science Chapter 13 Exercise Solution’ using the download button.

### Chapter 13: Magnetic Effects of Electric Current

In the previous Chapter on ‘Electricity,’ we learned about the healing effects of electric current. What could be the other effects of electric current?

We know that an electric current-carrying wire behaves like a magnet. Let us perform the following Activity to reinforce it.

We see that the needle is deflected. What does it mean? It means that the electric current through the copper wire has produced a magnetic effect. Thus we can say that electricity and magnetism are linked to each other.

Then, what about the reverse possibility of an electric effect of moving magnets? In this chapter, we will study magnetic fields and such electromagnetic effects.

We shall also study electromagnets and electric motors which involve the magnetic effect of electric current, and electric generators which involve the electric effect of moving magnets.

#### 13.1 Magnetic Field And Field Lines

We are familiar with the fact that a compass needle gets deflected when brought near a bar magnet.

A compass needle is, in fact, a small bar magnet. The ends of the compass needle point approximately in north and south directions.

The end pointing towards the north is called north seeking or north pole. The other end that points towards the south are called south seeking or south pole.

Through various activities, we have observed that like poles repel, while unlike poles of magnets attract each other.

The iron filings arrange themselves in a pattern as shown in Fig. 13.2. Why do the iron filings arrange in such a pattern? What does this pattern demonstrate?

The magnet exerts its influence in the region surrounding it. Therefore the iron filings experience a force.

The force thus exerted makes iron filings arranged in a pattern. The region surrounding a magnet, in which the force of the magnet can be detected, is said to have a magnetic field. The lines along which the iron filings align themselves represent magnetic field lines.

### NCERT Solutions Class 10 Science Chapter 13 Magnetic Effects of Electric Current

1. Which of the following property of a proton can change while it moves freely in a magnetic field? (There may be more than one correct answer.)

1. Mass
2. Speed
3. Velocity
4. Momentum

Solution:

(c) and (d)

When a proton enters the region of the magnetic field, it experiences a magnetic force. Due to this the path of the proton becomes circular. As a result, the velocity and the momentum change.

2. In Activity 13.7, how do we think the displacement of rod AB will be affected if (i) current in rod AB is increased; (ii) a stronger horse-shoe magnet is used; and (iii) length of the rod AB is increased?

Solution:

A current-carrying conductor when placed in a magnetic field experiences force. The magnitude of this force will increase with the increase in the amount of current, length of conductor, and the strength of the magnetic field. Hence, the strength of the magnetic force exerted on the rod AB and its displacement will increase if

1. The current in rod AB is increased
2. A stronger horseshoe magnet is used
3. When the length of the rod AB increases

3. A positively-charged particle (alpha-particle) projected towards the west is deflected towards the north by a magnetic field. The direction of the magnetic field is

1. towards south
2. towards east
3. downward
4. upward

Solution:

The direction of the magnetic field can be determined using Fleming’s Left-hand rule.

According to the rule, if we arrange our thumb, forefinger, and the middle finger of the left-hand right perpendicular to each other, then the thumb points towards the direction of the magnetic force, the middle finger the direction of the current, and the forefinger the direction of the magnetic field.

Since the direction of a positively charged particle is towards the west, the direction of the current will also be towards the west.

The direction of the magnetic force is towards the north, hence the direction of the magnetic field will be upward according to Fleming’s Left-hand rule.

In-text 13.4 Page:233

1. State Fleming’s left-hand rule.

Solution:

Fleming’s Left-hand rule states that if we arrange our thumb, forefinger, and middle finger of the left hand at right angles to each other, then the thumb points towards the direction of the magnetic force, the forefinger points towards the direction of the magnetic field and the middle finger points towards the direction of the current.

2. What is the principle of an electric motor?

Solution:

The working principle of the electric motor is based on the magnetic effect of current. A current-carrying conductor when placed in a magnetic field experiences force and rotates. The direction of the rotation of the conductor can be determined by Fleming’s Left-hand rule.

3. What is the role of a split ring in an electric motor?

Solution:

The split ring plays the role of commutator in an electric motor. The commutator reverses the direction of the current flowing through the coil after each half rotation of the coil. Due to this reversal of current, the coil continues to rotate in the same direction.

In text 13.5 Page:236

1. Explain different ways to induce a current in a coil.

Solution:

Following are the different ways to induce a current in a coil:

• If the coil is moved rapidly between the two poles of the horseshoe magnet, electric current is induced in the coil.
• When a magnet is moved relative to the coil, an electric current is induced in the coil.

In text 13.6 Page:237

1. State the principle of an electric generator.

Solution:

The electric generator works on the principle of electromagnetic induction. In a generator, electricity is generated by rotating a coil in the magnetic field.

2. Name some sources of direct current.

Solution:

DC generators and cells are some sources of direct current.

3. Which sources produce alternating current?

Solution:

Power plants and AC generators are some of the sources that produce alternating currents.

4. Choose the correct option.

A rectangular coil of copper wires is rotated in a magnetic field. The direction of the induced current changes once in each

1. two revolutions
2. one revolution
3. half revolution
4. one-fourth revolution

Solution:

c. half revolution

When a rectangular coil is rotated in a magnetic field, the direction of the induced current changes once in half revolution. As a result, the direction of the current in the coil remains the same.

Magnetic Effects of Electric Current NCERT Textbook With Solutions PDF Free Download