---
title: "NCERT Solutions Class 10 Science Magnetic Effects of Electric Current"
url: https://www.swavid.com/science/class/10/chapter/magnetic-effects-of-electric-current/ncert-solutions
dateModified: 2026-10-07T16:47:25+00:00
---

# NCERT Solutions Class 10 Science Magnetic Effects of Electric Current

This chapter's questions cover fundamental concepts of magnetic effects of electric current, including magnetic fields, right-hand thumb rules, solenoids, force on current-carrying conductors, and domestic electric circuits.

Free PDF (11 pages): https://www.swavid.com/api/seo/pdf/ncert/science/class-10/swavid-ncert-solutions-class-10-science-chapter-12-magnetic-effects-of-electric-current-5cc5cb02b7.pdf

## QUESTION

### Question 1

*2 marks · Very short answer*

Why does a compass needle get deflected when brought near a bar magnet?

**Solution**

1. A compass needle is a small bar magnet whose ends point in north and south directions.
2. When brought near a bar magnet, the magnetic field of the bar magnet exerts a magnetic force on the compass needle, causing it to deflect.

**Answer:** A compass needle gets deflected because the magnetic field of the bar magnet exerts a force on the magnetic poles of the compass needle.

> Common mistake: Stating that the compass needle gets deflected due to electric current instead of magnetic force from the bar magnet.

## QUESTIONS

### Question 1

*2 marks · Very short answer*

Draw magnetic field lines around a bar magnet.

**Solution**

1. Diagram: Draw a bar magnet with North (N) and South (S) poles.
2. Draw continuous closed curves emerging from the north pole and entering the south pole outside the magnet, and from south to north inside the magnet.

**Answer:** Magnetic field lines form closed curves emerging from the north pole and merging at the south pole.

> Common mistake: Drawing arrows in the wrong direction or not showing closed loops inside the magnet.

### Question 2

*3 marks · Short answer*

List the properties of magnetic field lines.

**Solution**

1. Magnetic field lines emerge from the north pole and merge at the south pole outside the magnet.
2. The relative strength of the magnetic field is indicated by the degree of closeness of the field lines.
3. No two magnetic field lines can intersect each other.

**Answer:** Magnetic field lines are closed curves, their crowding shows field strength, and they never intersect.

> Common mistake: Forgetting to mention that they are closed loops extending inside the magnet.

### Question 3

*3 marks · Short answer*

Why don't two magnetic field lines intersect each other?

**Solution**

1. If two magnetic field lines intersected, it would mean that at the point of intersection, the compass needle points in two directions.
2. The direction of the magnetic field at a single point is always unique.
3. Since pointing in two directions simultaneously is not possible, two magnetic field lines never cross each other.

**Answer:** Two magnetic field lines never intersect because it would imply two directions of the magnetic field at the same point, which is impossible.

> Common mistake: Failing to state that a compass needle cannot point in two directions at the same time.

## QUESTIONS

### Question 1

*3 marks · Short answer*

Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop.

**Part (i)**

1. Consider small sections of the circular loop carrying a clockwise current.
2. Applying the right-hand thumb rule at every point inside the loop, the magnetic field lines point into the plane of the table.

Answer (i): Inside the loop, the magnetic field is directed perpendicularly into the table.

**Part (ii)**

1. Applying the right-hand thumb rule outside the circular loop, the concentric field lines loop around the wire.
2. This makes the magnetic field emerge out of the plane of the table outside the loop.

Answer (ii): Outside the loop, the magnetic field is directed perpendicularly out of the table.

**Answer:** The magnetic field is directed perpendicularly into the table inside the loop and perpendicularly out of the table outside the loop.

> Common mistake: Confusing the direction inside and outside the loop by not applying the right-hand thumb rule correctly.

### Question 2

*2 marks · Very short answer*

The magnetic field in a given region is uniform. Draw a diagram to represent it.

**Solution**

1. A uniform magnetic field in a given region is represented by parallel, equidistant straight lines.
2. Diagram: Draw a set of parallel straight lines pointing in the same direction, spaced equally apart.

**Answer:** A uniform magnetic field is represented by parallel and equidistant straight lines.

> Common mistake: Drawing converging or diverging lines, which represent a non-uniform magnetic field.

### Question 3

*1 mark · MCQ*

Choose the correct option. The magnetic field inside a long straight solenoid-carrying current

- is zero.
- decreases as we move towards its end.
- increases as we move towards its end.
- is the same at all points.

**Solution**

1. The magnetic field lines inside a long straight current-carrying solenoid are in the form of parallel straight lines.
2. Parallel field lines indicate that the magnetic field is the same at all points inside the solenoid, making it uniform.

**Answer:** (d) is the same at all points.

> Common mistake: Choosing zero, confusing the inside of a solenoid with the inside of a hollow conductor.

## QUESTIONS

### Question 1

*1 mark · MCQ*

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.)

- mass
- speed
- velocity
- momentum

**Solution**

1. A magnetic field exerts a force on a moving charge that is perpendicular to its velocity, changing its direction of motion while keeping its speed constant.
2. Since velocity and momentum depend on direction, both change, while mass and speed remain unchanged.
3. Thus, the correct options are (c) velocity and (d) momentum.

**Answer:** (c) velocity and (d) momentum

> Common mistake: Students often assume speed changes because force acts on the particle.

### Question 2

*3 marks · Short answer*

In Activity 12.7, 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?

**Part (i)**

1. The force on a current-carrying conductor in a magnetic field is directly proportional to the current.
2. When the current in rod AB is increased, the magnetic force increases, leading to a larger displacement.

Answer (i): Displacement increases.

**Part (ii)**

1. The magnetic force is directly proportional to the strength of the magnetic field.
2. Using a stronger horse-shoe magnet increases the magnetic field strength, thereby increasing the force and displacement of the rod.

Answer (ii): Displacement increases.

**Part (iii)**

1. The force on the conductor is directly proportional to its length inside the magnetic field.
2. Increasing the length of rod AB increases the magnitude of the force acting on it, resulting in a larger displacement.

Answer (iii): Displacement increases.

**Answer:** The displacement of rod AB increases in all three cases.

> Common mistake: Forgetting that force depends on current, magnetic field strength, and length of the conductor simultaneously.

### Question 3

*1 mark · MCQ*

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

- towards south
- towards east
- downward
- upward

**Solution**

1. According to Fleming's left-hand rule, stretch the thumb, forefinger, and middle finger of the left hand mutually perpendicular to each other.
2. The direction of current for a positively charged alpha-particle is the same as its direction of motion (towards west), so the middle finger points west, and the thumb (force/deflection) points north.
3. Aligning the left hand shows that the first finger (magnetic field) must point vertically upward.

**Answer:** (d) upward

> Common mistake: Confusing the direction of motion of a positive charge with that of an electron.

## QUESTIONS

### Question 1

*2 marks · Very short answer*

Name two safety measures commonly used in electric circuits and appliances.

**Solution**

1. The two common safety measures used in domestic electric circuits and appliances are the use of an electric fuse and earthing of metallic appliances.
2. An electric fuse prevents damage due to overloading or short-circuiting, while earthing protects the user from severe electric shocks.

**Answer:** Use of electric fuse and earthing of metallic appliances.

> Common mistake: Only writing the names of safety devices without mentioning their basic purpose.

### Question 2

*3 marks · Short answer*

An electric oven of 2 kW power rating is operated in a domestic electric circuit (220 V) that has a current rating of 5 A. What result do you expect? Explain.

**Solution**

1. Given power rating $P = 2\text{ kW} = 2000\text{ W}$ and potential difference $V = 220\text{ V}$.
2. The current drawn by the electric oven is calculated using the formula $I = \frac{P}{V}$.
3. Substituting the values, $I = \frac{2000\text{ W}}{220\text{ V}} = 9.09\text{ A}$.
4. Since the current drawn ($9.09\text{ A}$) exceeds the current rating of the circuit ($5\text{ A}$), the fuse will melt and break the circuit.

**Answer:** The fuse will melt and break the circuit because the current drawn (9.09 A) exceeds the 5 A rating.

> Common mistake: Forgetting to convert kW to W before calculating the current.

### Question 3

*3 marks · Short answer*

What precaution should be taken to avoid the overloading of domestic electric circuits?

**Solution**

1. Overloading occurs when too many appliances of high power rating are connected to a single socket or when live and neutral wires touch.
2. To avoid overloading, too many appliances should not be connected to a single socket simultaneously.
3. High power rating appliances such as geysers, air conditioners, and electric ovens should not be operated at the same time.

**Answer:** Do not connect too many high-power appliances to a single socket or operate them simultaneously.

> Common mistake: Confusing overloading with short-circuiting.

## EXERCISES

### Question 1

*1 mark · MCQ*

Which of the following correctly describes the magnetic field near a long straight wire?

- The field consists of straight lines perpendicular to the wire.
- The field consists of straight lines parallel to the wire.
- The field consists of radial lines originating from the wire.
- The field consists of concentric circles centred on the wire.

**Solution**

1. The magnetic field lines around a current-carrying straight wire consist of a series of concentric circles.
2. Therefore, option (d) is the correct description.

**Answer:** (d) The field consists of concentric circles centred on the wire.

> Common mistake: Confusing concentric circles with radial or parallel lines.

### Question 2

*1 mark · MCQ*

At the time of short circuit, the current in the circuit

- reduces substantially.
- does not change.
- increases heavily.
- vary continuously.

**Solution**

1. When the live wire and the neutral wire come into direct contact, a short circuit occurs.
2. In this situation, the current in the circuit abruptly increases heavily.

**Answer:** (c) increases heavily.

> Common mistake: Thinking that current decreases during a short circuit.

### Question 3

*2 marks · True or false*

State whether the following statements are true or false.
(a) The field at the centre of a long circular coil carrying current will be parallel straight lines.
(b) A wire with a green insulation is usually the live wire of an electric supply.

**Part (a)**

1. At the centre of a circular loop carrying current, the arcs of the concentric circles appear as straight lines.

Answer (a): True

**Part (b)**

1. A wire with green insulation is used as the earth wire for safety, while the live wire has red insulation.

Answer (b): False

**Answer:** (a) True, (b) False

> Common mistake: Confusing the color coding of live and earth wires in domestic circuits.

### Question 4

*2 marks · Very short answer*

List two methods of producing magnetic fields.

**Solution**

1. A magnetic field can be produced by using a permanent magnet.
2. A magnetic field can also be produced by passing an electric current through a conductor, such as a straight wire, a circular loop, or a solenoid.

**Answer:** Two methods of producing magnetic fields are by using a permanent magnet and by using a current-carrying conductor.

> Common mistake: Listing appliances instead of the underlying physical methods.

### Question 5

*2 marks · Very short answer*

When is the force experienced by a current-carrying conductor placed in a magnetic field largest?

**Solution**

1. The force experienced by a current-carrying conductor placed in a magnetic field depends on the angle between the direction of current and the magnetic field.
2. The magnitude of the force is highest when the direction of current is at right angles to the direction of the magnetic field.

**Answer:** The force is largest when the direction of current is at right angles to the direction of the magnetic field.

> Common mistake: Stating parallel instead of perpendicular.

### Question 6

*3 marks · Short answer*

Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of magnetic field?

**Solution**

1. The electron beam moves from the back wall to the front wall, which means the conventional current flows in the opposite direction, from the front wall to the back wall.
2. The deflection of the electron beam is to the right side of the observer, which represents the direction of the force acting on the electron.
3. Applying Fleming's left-hand rule, with the second finger pointing towards the back wall (direction of current) and the thumb pointing to the right (direction of force), the forefinger points vertically downwards.

**Answer:** The direction of the magnetic field is vertically downwards.

> Common mistake: Taking the direction of electric current to be the same as the direction of motion of electrons, instead of taking it opposite.

### Question 7

*4 marks · Case-based*

State the rule to determine the direction of a (i) magnetic field produced around a straight conductor-carrying current, (ii) force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it, and (iii) current induced in a coil due to its rotation in a magnetic field.

**Part (i)**

1. Imagine holding a current-carrying straight conductor in your right hand such that your thumb points in the direction of current.
2. Your fingers will wrap around the conductor in the direction of the magnetic field lines.

Answer (i): Right-hand thumb rule

**Part (ii)**

1. Stretch the thumb, forefinger, and middle finger of your left hand such that they are mutually perpendicular.
2. If the first finger points in the direction of magnetic field and the second finger in the direction of current, then the thumb points in the direction of force.

Answer (ii): Fleming's left-hand rule

**Part (iii)**

1. Stretch the thumb, forefinger, and middle finger of your right hand to be mutually perpendicular.
2. If the forefinger points in the direction of magnetic field and the thumb points in the direction of motion of the conductor, then the middle finger points in the direction of induced current.

Answer (iii): Fleming's right-hand rule

**Answer:** Right-hand thumb rule, Fleming's left-hand rule, and Fleming's right-hand rule.

> Common mistake: Mixing up left-hand and right-hand rules for force and induced current.

### Question 8

*2 marks · Very short answer*

When does an electric short circuit occur?

**Solution**

1. An electric short circuit occurs when the live wire and the neutral wire come into direct contact.
2. This happens due to damage in the insulation of wires or a fault in the appliance, causing the current in the circuit to abruptly increase.

**Answer:** A short circuit occurs when the live wire and neutral wire come into direct contact due to damaged insulation or a fault.

> Common mistake: Confusing short-circuiting with overloading due to connecting too many appliances.

### Question 9

*3 marks · Short answer*

What is the function of an earth wire? Why is it necessary to earth metallic appliances?

**Solution**

1. The earth wire has green insulation and is connected to a metal plate deep in the earth near the house.
2. Its function is to provide a low-resistance conducting path for any leakage of current from the metallic body of an appliance.
3. It is necessary to earth metallic appliances so that any accidental current leakage keeps the potential of the appliance to that of the earth, protecting the user from a severe electric shock.

**Answer:** Earth wire provides a safe low-resistance path to the ground for leaked current, preventing severe electric shocks from metallic appliances.

> Common mistake: Stating that the earth wire carries regular operating current instead of leakage current.

## Frequently asked questions

### How many total questions are there in the NCERT Solutions for Class 10 Science Chapter 12?

This chapter contains 13 textual questions across various sections and 9 exercise questions at the end. You can find SwaVid's free PDF and step-by-step solutions for all these questions on this page only.

### Which important topics are covered in the questions of this chapter?

The questions cover key concepts such as the magnetic field of a bar magnet, magnetic field lines and their properties, and the magnetic field due to circular loops and solenoids. Other major topics include Fleming's left-hand rule, force on a current-carrying conductor, domestic electric circuits, and safety measures like fuse ratings.

### What are the hardest question types in these solutions and how should I approach them?

Case-based and numerical questions involving Fleming's left-hand rule or current calculations are often considered the trickiest. To approach them, first list the given values, identify the correct electromagnetism rule such as $\vec{F} = I(\vec{L} \times \vec{B})$, and apply step-by-step reasoning as shown in SwaVid's free PDF on this page.

### How can I write answers for full marks in Class 10 board exams for this chapter?

To secure full marks, structure your answers clearly by defining the physical terms, stating relevant rules like Fleming's left-hand rule precisely, and drawing neat diagrams for magnetic field lines where required. Following the structured formats in SwaVid's free PDF and step-by-step solutions available on this page will help you achieve this.

### Is a free PDF available for Chapter 12 Magnetic Effects of Electric Current?

Yes, SwaVid provides a comprehensive free PDF and step-by-step solutions for this chapter based on the NCERT textbook for the 2026-27 session. You can easily access and download all the solved textual and exercise questions directly from this page.

## Related pages

- [Exercise EXERCISES solutions](https://www.swavid.com/science/class/10/chapter/magnetic-effects-of-electric-current/ncert-solutions/exercise-exercises)
- [Magnetic Effects of Electric Current: CBSE previous year questions](https://www.swavid.com/cbse/class-10/science/pyq/magnetic-effects-of-electric-current)
- [Class 10 Science chapters](https://www.swavid.com/science/class/10)

Solutions written by SwaVid, a personal AI tutor for Class 6 to 10 Maths and Science. Practise this chapter free: https://www.swavid.com/start/student