NCERT Solutions Class 10 Science Chapter 12 Magnetic Effects of Electric Current

NCERT Solutions for Science Chapter 12, "Magnetic Effects of Electric Current," is an essential resource for Class 10 students aiming to understand key concepts in science. This NCERT Solutions Chapter covers topics such as concepts of electromagnetism, the magnetic field produced by a current-carrying conductor, electromagnetic induction, the force exerted on a current-carrying conductor in a magnetic field, and the functioning of electric motors and generators. By studying the questions and answers from this chapter, students can enhance their grasp of these important concepts and prepare well for the exams.

This blog provides detailed NCERT Solutions for all the exercises in this chapter, offering stepwise explanations for effective learning.

1.0Download Class 10 NCERT Solutions Chapter 12 Magnetic Effects of Electric Current: Free PDF 

As you know, NCERT solutions are helpful, so you must practice them as much as possible. However, the question arises of how you can access them. Don't worry; here, we are providing you with the free PDF of NCERT solutions for Class 10 Science Chapter 12: Magnetic Effects of Electric Current.

2.0NCERT Solutions for Class 10 Science Chapter 12 Magnetic Effects of Electric Current: Overview

3.0Oersted’s Experiment

• They found that a compass needle is deflected when an electric current travels through a metallic wire placed nearby.
• Observations show that electricity and magnetism were related phenomena.

Magnetic Field: The magnetic field is the area around a magnet where its influence affects other magnetic materials. It is measured in Teslas (T).

Magnetic Field Lines: These lines extend from the north pole of a magnet, curve around, and return to the south pole  forming closed loops. They are densest near the poles and never intersect. The direction of the magnetic field at any point is indicated by the tangent to the field lines at that point.

Domestic Electric Circuits

Electric power to a house is supplied via overhead wires or underground cables, with three main wires:

1. Live Wire (Brown/Red): Delivers current.
2. Neutral Wire (Light Blue/Black): Returns current, at zero potential.
3. Earth Wire (Green/Yellow): Grounds the system for safety.

The voltage between the live and neutral wires is 220V. At the substation, the neutral and earth wires are at the same potential. A fuse in the live wire, rated for the house's load, protects the system before it enters the house. After passing through an energy meter, the power is routed through a distribution board with fuses to different circuits. Each appliance is connected in parallel, ensuring consistent 220V.

Fuses protect circuits by melting if the current exceeds safe levels. Short circuits occur when the live and neutral wires directly connect, while overloading happens when too many appliances are on one circuit or exceed its capacity.

4.0Class 10 Science Chapter 12 Magnetic Effects of Electric Current NCERT : Detailed Solutions

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

Solution

A compass needle is a small magnet which experiences a force in the magnetic field of a bar magnet. Due to this force, it gets deflected.

2. Draw magnetic field lines around a bar magnet.

Solution

3. List the properties of magnetic lines of force.

Solution

(i) Magnetic lines of force are closed continuous curves.

(ii) The tangent at any point on the magnetic line of force gives the direction of the magnetic field at that point.

(iii) Two magnetic lines of force never cross each other.

4. Why don't two magnetic lines of force intersect each other?

Solution

The tangent at any point on a magnetic field line gives the direction of magnetic field at that point. If two magnetic field lines cross each other, then at the point of intersection, there will be two tangents. Hence, there will be two directions of the magnetic field at the point of intersection. This is not possible. Hence, no two magnetic field lines can cross each other.

5. 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.

Solution

The magnetic field inside the loop is perpendicular to the plane of the table and in the downward direction. Outside the loop, the magnetic field is perpendicular to the plane of the table and in the upward direction.

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

Solution

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

(1) is zero

(2) decreases as we move towards its ends

(3) increases as we move towards its ends

(4) is the same at all points

Solution

The magnetic field inside a long straight solenoid carrying current decreases as we move towards its ends.

At the ends of the solenoid, the strength of the magnetic field is almost half that in the middle of the solenoid. Thus, the correct option is (2).

8. Which of the following properties 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

Motion of a charged particle like a proton in a magnetic field is a circular path. Hence, its velocity and momentum can change. Thus, option (3) and (4) are correct.

9. In active physics 6 , how do we think the displacement of rod PQ will be affected if (i) current in rod PQ is increased (ii) a stronger horseshoe magnet is inserted (iii) length of the rod PQ is increased.

Solution

(i) When the current in the rod increases, force on the rod also increases. Hence, the displacement of the rod increases.

(ii) When a stronger horseshoe magnet is inserted, the magnetic field increases. Thus, force on the rod also increases. Hence, displacement of the rod increases.

(iii) When length of the rod increases, force on the rod also increases and hence, displacement increases.

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

(1) towards south

(2) towards east

(3) downward

(4) upward

Solution

By applying Fleming's left-hand rule, we find that the magnetic field is in upward direction.

Thus, option (4) is correct.

11. Name two safety measures commonly used in electric circuits and appliance.

Solution

The two safety measures commonly used in electric circuits and appliances are fuse and earthing.

12. 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

Given,

P=2kw=2000 W,I=5 A, V=220 V

P=V×I⇒I=VP​=2202000​=9 A

If there is no fuse, overloading will result in wire melting, which will cause a short circuit, which will start a fire. As a result, the current will exceed and the fuse will burn out.

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

Solution

For the purpose of preventing overloading and short circuits, the fuse in the circuit should always be connected. Avoid plugging in too many appliances at once since this could start a fire. Always operate equipment within an electric circuit's safe limit. Use only one appliance at a time, always.

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

(1) The field consists of a straight line perpendicular to the wire.

(2) The field consists of straight lines parallel to the wire.

(3) The field consists of radial lines originating from the wire.

(4) The field consists of concentric circles centred on the wire.

Solution

The magnetic field near a long straight

on the wire.

Hence, option (4) is correct.

15. At the time of short circuit. the current the circuit

(1) reduces substantially.

(2) does not change.

(3) increases heavily.

(4) vary continuously.

Solution

Short circuit means there is no voltage difference between the two points in the circuit. Hence by ohms law large current flows through it. So, at the time of the short circuit, the current in the circuit increases heavily.

Hence, option (3) is correct.

16. State whether the following statements are true or false.

(i) The field at the centre of a long circular coil carrying current will be parallel straight lines.

(ii) A wire with a green insulation of usually the live wire of an electric supply.

Solution

(i) True

The field at the centre of a long circular coil carrying current will be parallel straight lines.

(ii) False

17. A wire with a green insulation of usually the earth wire of an electric supply.

List two methods of producing magnetic fields.

Solution

(i) A permanent magnet.

(ii) A current-carrying solenoid.

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

Solution

When the current-carrying conductor is placed perpendicular to the magnetic field.

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

Solution

The movement of an electron beam from the back wall to the front wall is equivalent to the flow of electric current from the front wall to the back wall. The deflection of the beam means the force is acting towards our right side. According to Fleming's LeftHand Rule, the direction of the magnetic field is vertically downward.

20. 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.

Solution

(i) Right hand thumb rule.

(ii) Fleming's left-hand rule.

21. When does an electric short-circuit occur?

Solution

When live wire and neutral wire touch each other (i.e. come in direct contact).

22. What is the function of an earth wire? Why is it necessary to earth metallic casings of electric appliances?

Solution

Earth wire acts as a safety measure. When the live wire touches the metallic casing of an electric appliance, the electric current flows from the casing of the appliance to the earth through the copper wire. An electric current flows along the path of low resistance thus, current passes through the copper wire instead of the human body. Thus, the human body is saved from electric shock.

5.0Benefits of Magnetic Effects of Electric Current

• Clear Understanding of Concepts: This Chapter Magnetic Effects of Electric Current explain important topics like electromagnetism, the magnetic field produced by a current-carrying conductor, and electromagnetic induction in an easy way.
• Step-by-Step Learning: This NCERT Solutions Class 10 Science provides detailed, step-by-step answers, helping students solve questions more effectively and improving their problem-solving skills.
• Boosts Exam Preparation: By following the solutions, students can prepare well for exams as the content is based on the CBSE syllabus, making it relevant for the board exams.
• Builds Strong Foundation: Learning these concepts helps build a strong base in science, which will be useful in higher grades.
• Simplifies Complex Topics: Tough topics like magnetic fields, field lines, and electromagnetic induction are simplified, making them easier for students to understand.