Important Questions for Class 10 Science Chapter 12: Magnetic Effects of Electric Current

Magnetic Effects of Electric Current is Chapter 12 of Class 10 Science. It explains how electric current produces a magnetic field, how that field interacts with conductors, and how this principle applies to devices and domestic circuits. The chapter connects electricity with magnetism and forms the foundation for understanding motors, electromagnets, and circuit safety.

Important Questions for Class 10 Science Chapter 12 cover magnetic field lines, right-hand thumb rule, Fleming's left-hand rule, solenoids, and domestic wiring: all regular board exam topics. Questions and answers are organised by topic and question type so you can revise Chapter 12 in the most effective order.

A student who can apply Fleming's left-hand rule to an unfamiliar direction problem, draw a solenoid field diagram, and explain the function of the earth wire in a domestic circuit will handle every question type from this chapter in CBSE 2026 papers. All questions and answers are available section by section below. 

Key Takeaways

Introduction to Class 10 Science Chapter 12

Before this chapter, electricity and magnetism were separate topics. Chapter 12 shows they are connected: a current-carrying conductor produces a magnetic field, and a conductor placed in a magnetic field experiences a force. These two facts power every device from electric motors to MRI machines.

The chapter tests three skills in CBSE 2026 board papers: applying directional rules (right-hand thumb rule and Fleming's left-hand rule), drawing and interpreting magnetic field diagrams, and explaining domestic circuit safety. Students who practise all three skills separately before combining them in full answers score consistently better.

Start your revision with NCERT Solutions for Class 10 Science Chapter 12 to strengthen concept clarity before practising these important questions.

Important Topics in Class 10 Science Chapter 12

Every board question from this chapter maps to one of these areas. Use this as a checklist: tick each topic only after you can answer a 3-mark question on it without looking at notes.

Magnetic Field and Field Lines Important Questions

Magnetic field line properties are a frequent 1-mark and 2-mark source in CBSE 2026 papers. These magnetic field class 10 important questions are drawn directly from the NCERT chapter properties list.

Q1. What is a magnetic field? A magnetic field is the region surrounding a magnet or current-carrying conductor in which the force of the magnet can be detected.

Q2. List four properties of magnetic field lines. They emerge from the north pole and merge at the south pole outside the magnet. Inside the magnet, they run from the south pole to the north pole. They are closed curves. No two field lines intersect each other. The closeness of field lines indicates the strength of the magnetic field.

Q3. Why do two magnetic field lines never intersect each other? Two magnetic field lines never intersect because if they did, there would be two directions of the magnetic field at the same point. This is not possible since the magnetic field has a unique direction at every point in space.

Q4. What does the density of magnetic field lines indicate? The density of magnetic field lines indicates the relative strength of the magnetic field. Where field lines are closer together, the field is stronger. Where they are farther apart, the field is weaker.

Q5. Why does a compass needle get deflected when brought near a bar magnet? A compass needle is a small bar magnet. When brought near a bar magnet, its magnetic field lines interact with those of the bar magnet. Unlike poles attract and like poles repel, causing the compass needle to align with the field.

Right Hand Thumb Rule Class 10 Questions: Current-Carrying Conductor

The pattern of magnetic field around different shapes of conductors is a core exam topic. Right hand thumb rule class 10 questions appear as direct 1-mark statements or application-based 2-mark problems.

Q1. What is the shape of the magnetic field lines around a straight current-carrying conductor? The magnetic field lines around a straight current-carrying conductor are concentric circles centred on the conductor.

Q2. How does the strength of the magnetic field around a straight conductor change with distance and current? The strength of the magnetic field increases as the current through the conductor increases. It decreases as the distance from the conductor increases.

Q3. State the right-hand thumb rule. If you hold a current-carrying straight conductor in your right hand such that the thumb points in the direction of the current, your fingers wrap around the conductor in the direction of the magnetic field lines.

Q4. A current through a horizontal power line flows in the east to west direction. What is the direction of the magnetic field at a point directly below it? Applying the right-hand thumb rule, the magnetic field at that point is directed from west to east.

Q5. What happens to the direction of the magnetic field when the direction of current through a straight wire is reversed? The direction of the magnetic field also reverses when the direction of current through the conductor is reversed.

Solenoid Class 10 Questions: Circular Loop, Solenoid, and Electromagnet

These questions test the ability to connect conductor shape with field pattern. Solenoid class 10 questions frequently appear as 3-mark answers requiring both description and comparison with a bar magnet.

Q1. What is the shape of the magnetic field at the centre of a current-carrying circular loop? At the centre of a circular current-carrying loop, the magnetic field lines appear as straight lines. The concentric circles become so large at the centre that their arcs appear straight.

Q2. How does the number of turns in a circular coil affect the magnetic field it produces? If a circular coil has n turns, the magnetic field produced is n times as large as that produced by a single turn. The current in each turn has the same direction, and the field due to each turn adds up.

Q3. What is a solenoid? How does its magnetic field compare to that of a bar magnet? A solenoid is a coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder. The pattern of the magnetic field lines around a current-carrying solenoid is similar to that of a bar magnet. One end behaves as a north pole and the other as a south pole. The field inside is uniform: the lines are parallel straight lines.

Q4. What is an electromagnet? How is it made? An electromagnet is a magnet formed when a piece of magnetic material, such as soft iron, is placed inside a current-carrying solenoid. The strong and uniform magnetic field inside magnetises the iron core. When the current is switched off, the iron loses its magnetism.

Electromagnets also have medical applications. The magnetic field produced by currents in the body forms the basis of MRI, a diagnostic technique mentioned in the NCERT chapter.

Q5. State three factors on which the magnetic field produced by a current-carrying solenoid depends. The magnetic field depends on: the strength of the current flowing through the solenoid; the number of turns of wire in the solenoid; the nature of the material placed inside the solenoid.

Q6. The magnetic field inside a long straight solenoid carrying current is: (a) Zero (b) Decreasing towards its ends (c) Increasing towards its ends (d) The same at all points (d) The same at all points. Field lines inside the solenoid are parallel straight lines, showing a uniform field.

Force on a Current-Carrying Conductor and Fleming's Left Hand Rule Class 10

Force on a conductor questions connect theoretical magnetic field understanding to practical applications. These electromagnet class 10 questions and Fleming's left hand rule Class 10 problems are consistently tested in CBSE 2026 board papers.

Q1. What happens when a current-carrying conductor is placed in a magnetic field? A current-carrying conductor placed in a magnetic field experiences a force. The direction and magnitude depend on the direction of the current, the direction of the field, and the length of the conductor.

Q2. When is the force on a current-carrying conductor placed in a magnetic field the largest? The force is the largest when the direction of the current is perpendicular to the direction of the magnetic field.

Q3. How does the displacement of a current-carrying rod in a magnetic field change if:

(a) Current in the rod is increased: The force increases, so the displacement of the rod increases. (b) A stronger horseshoe magnet is used: A stronger magnet means a stronger magnetic field; the force and displacement increase. (c) The length of the rod is increased: A longer conductor in the same field with the same current experiences a greater force; displacement increases.

Q4. State Fleming's left-hand rule. If you stretch the thumb, forefinger, and middle finger of your left hand such that they are mutually perpendicular, and if the forefinger points in the direction of the magnetic field and the middle finger in the direction of the current, then the thumb points in the direction of the force on the conductor.

Q5. An electron enters a magnetic field at right angles to it. The magnetic field is directed into the page and the electron moves downward. What is the direction of force on the electron? The direction of current is opposite to electron motion, so conventional current is upward. With field into the page and current upward, applying Fleming's left-hand rule gives force directed to the right. Since the charge is negative, the actual force on the electron is directed to the left.

Q6. Name two devices that use the principle that a current-carrying conductor experiences a force in a magnetic field. Electric motor and galvanometer. Loudspeakers and measuring instruments are other examples.

Domestic Electric Circuits Class 10 Questions

Domestic circuit questions carry 3-mark and 5-mark marks regularly in CBSE 2026 papers. Domestic electric circuits class 10 questions test safety devices, wire colour codes, and overloading: the three most tested sub-topics from this section.

Q1. Describe the domestic electric circuit in India. In Indian homes, electric power arrives through two wires. The live wire has red insulation and the neutral wire has black insulation. The potential difference between them is 220 V.

These wires pass through a main fuse and electricity meter at the meter board. From there, they connect to two separate circuits: one of 15 A rating for high-power appliances and one of 5 A rating for lights and fans.

A third wire, the earth wire (green insulation), connects to a metal plate buried in the ground. All appliances in a circuit are connected in parallel.

Q2. What is the function of an earth wire? Why is it necessary to earth metallic appliances? The earth wire provides a low-resistance conducting path for any leakage current. For metallic appliances like electric presses, the metallic body is connected to the earth wire. If current leaks to the metallic body, it flows through the earth wire to the ground, preventing severe electric shock.

Q3. What are the standard colour codes for wires in domestic circuits? Live wire: red insulation. Neutral wire: black insulation. Earth wire: green insulation.

Q4. What is short-circuiting? When does it occur? Short-circuiting occurs when the live wire and the neutral wire come into direct contact. This happens when wire insulation is damaged or there is a fault in the appliance. The current in the circuit increases abruptly during a short circuit.

Q5. What is overloading in a domestic circuit? How can it be prevented? Overloading occurs when too many high-power appliances are connected to a single socket or when there is an accidental rise in supply voltage. The current in the circuit rises beyond safe limits. Prevention: use separate circuits for high-power and low-power appliances and use a fuse of appropriate current rating.

Q6. Why is the earth pin in a three-pin plug thicker and longer than the live and neutral pins? The earth pin is longer so that it connects to the earth terminal before the live and neutral pins connect. This ensures earthing is established first. It is thicker so that it cannot accidentally be inserted into the live or neutral socket holes.

Q7. An electric oven of 2 kW power rating is operated in a domestic circuit of 220 V with a 5 A current rating. What result do you expect? Power = 2000 W, Voltage = 220 V. Current drawn = P/V = 2000/220 = 9.09 A. The oven draws 9.09 A, which exceeds the 5 A circuit rating. This causes overloading and may damage the circuit due to overheating.

Class 10 Science Chapter 12 MCQ with Answers

These class 10 science chapter 12 MCQ questions cover every major concept in Chapter 12. Attempt each before checking the answer.

1. Which of the following correctly describes the magnetic field near a long straight wire? (a) Straight lines perpendicular to the wire (b) Straight lines parallel to the wire (c) Radial lines originating from the wire (d) Concentric circles centred on the wire (d) Concentric circles centred on the wire.
2. Magnetic field lines determine: (a) The shape of the magnetic field (b) Only the direction (c) Only the relative strength (d) Both the direction and the relative strength (d) Both the direction and the relative strength of the magnetic field.
3. At the time of short circuit, the current in the circuit: (a) Reduces substantially (b) Does not change (c) Increases heavily (d) Varies continuously (c) Increases heavily.
4. The magnetic field inside a long straight solenoid carrying current: (a) Is zero (b) Decreases towards its end (c) Increases towards its end (d) Is the same at all points (d) Is the same at all points.
5. A device used for producing electric current is called a: (a) Galvanometer (b) Motor (c) Generator (d) Ammeter (c) Generator.
6. Electric motor converts: (a) Mechanical energy into electrical energy (b) Mechanical energy into heat energy (c) Electrical energy into heat energy (d) Electrical energy into mechanical energy (d) Electrical energy into mechanical energy.
7. The potential difference between the live wire and the neutral wire in India is: (a) 200 V (b) 150 V (c) 210 V (d) 220 V (d) 220 V.
8. Forces acting on a stationary charge in a magnetic field B is: (a) BQv (b) BQ/v (c) Bv/Q (d) Zero (d) Zero. A stationary charge experiences no magnetic force.
9. The most important safety device used for protecting electrical appliances from short-circuiting or overloading is: (a) Earthing (b) Stabiliser (c) Electric meter (d) Fuse (d) Fuse.
10. When is the force on a current-carrying conductor placed in a magnetic field the largest? When the conductor is placed perpendicular to the direction of the magnetic field.

Important Formulas and Rules for Chapter 12

Students search this chapter heavily for rules, definitions, and quick reference points before CBSE 2026 exams.

Right-Hand Thumb Rule: Hold the current-carrying conductor in the right hand with the thumb pointing in the direction of current. The curled fingers show the direction of the magnetic field around the conductor.

Fleming's Left-Hand Rule: Stretch the thumb, forefinger, and middle finger of the left hand mutually perpendicular. Forefinger = direction of magnetic field (B). Middle finger = direction of current (I). Thumb = direction of force (F) on the conductor.

Magnetic Effects of Electric Current Class 10 PYQ Questions

These magnetic effects of electric current class 10 PYQ questions have appeared in previous CBSE board exams. Practising them tells you exactly what the examiner expects in terms of format, length, and accuracy.

Q1. State the rule to determine the direction of:

(i) Magnetic field produced around a straight conductor carrying current: Right-hand thumb rule. Hold the conductor in the right hand with the thumb pointing in the direction of current. The fingers give the direction of the magnetic field lines.

(ii) Force experienced by a current-carrying straight conductor placed in a magnetic field: Fleming's left-hand rule. Forefinger points in the direction of magnetic field, middle finger in the direction of current, and the thumb shows the direction of force.

(iii) Current induced in a coil due to its rotation in a magnetic field: Fleming's right-hand rule. Thumb points in the direction of motion, forefinger in the direction of the magnetic field, and the middle finger gives the direction of the induced current.

Q2. What is the function of an earth wire? Why is it necessary to earth metallic appliances? The earth wire provides a low-resistance path for leakage current. Metallic appliances connected to the earth wire stay at earth potential. Any leakage flows safely to the ground, preventing severe electric shock.

Q3. When does an electric short circuit occur? A short circuit occurs when the live wire and neutral wire come into direct contact due to damaged insulation or a fault in the appliance. The current in the circuit rises abruptly.

Q4. List two methods of producing magnetic fields. Using a permanent magnet or horseshoe magnet. Passing electric current through a conductor or coil (electromagnet).

Q5. Imagine you are sitting in a chamber with your back to one wall. An electron beam moves horizontally from the back wall towards the front wall and is deflected to your right side by a strong magnetic field. What is the direction of the magnetic field? An electron beam moving towards the front wall is equivalent to conventional current moving towards the back wall. The deflection is to the right. Applying Fleming's left-hand rule, the magnetic field acts vertically downward.