Bihar Board Class 10 · Science · Matric exam 2027
Chapter 13: Magnetic Effects of Electric Current
This chapter’s questions from Bihar Board (BSEB)’s real papers of 2021–2026 — the 17 asked most often, 3 with the full model answer, 14 with how the answer begins — and objective questions with the board’s key.
- marks a year (about)
- 3
- questions a year (about)
- 4
- rank in Science
- #13
From 6 years of papers, 2021–2026 · full chapter-wise marks
VVI questions — the ones the board asked most (17)
- Q1Short answer2 marksAsked: 2021, 2022, 2025
What do you understand by electromagnetic induction?
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Model answer · electromagnetic induction, definition
- 1.When there is a relative motion between a coil and a magnet placed near the coil, the magnetic field associated with the coil changes, and due to this changing magnetic field, an electric current is induced in the coil.1 mark
- 2.This phenomenon of production of induced current in a coil placed in a region where the magnetic field changes with time is called electromagnetic induction.1 mark
- Mention 'relative motion' between the coil and the magnet in the first line.
- Use the exact term 'electromagnetic induction' when naming the phenomenon.
- State that the induced current arises because the magnetic field changes with time.
Marks split from a structure derived from past papers (checked twice); not Bihar Board’s official scheme
- Q2Long answer6 marksAsked: 2025
Describe Oersted's experiment to show that a magnetic field is produced around a current carrying conductor wire.
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Model answer · Oersted's experiment, magnetic effect of current
- 1.In Oersted's experiment, a straight copper wire AB is connected in an electric circuit with a battery and a plug key, and this wire is placed in the North-South direction.1 mark
- 2.A magnetic needle, which is a compass, is placed just below the straight copper wire, parallel to it.1 mark
- 3.When electric current is passed through the wire by plugging the key, the magnetic needle gets deflected. If the current flows from north to south, the north pole of the compass needle moves towards the east.1.5 marks
- 4.On reversing the direction of current through the copper wire, that is, making it flow from south to north, the deflection of the magnetic needle occurs in the opposite direction, that is, the needle now moves towards the west.1.5 marks
- 5.This experiment proves that a magnetic field is produced around a current-carrying conductor, because the compass needle, which responds only to a magnetic field, gets deflected only when current flows through the wire, and the direction of this magnetic field also reverses when the direction of current is reversed.1 mark
Diagram: Draw a straight copper wire AB placed in the North-South direction connected in series with a battery and a plug key, with a magnetic compass needle placed just below and parallel to the wire; show the needle's deflection towards east when current flows north to south, labelling the wire, battery, plug key, compass needle, N, S, and the deflected direction.
- Write 'copper wire' and 'North-South' together while describing the wire's placement.
- State both deflection directions, 'east' and 'west', while describing reversal of current.
- End with the conclusion sentence using the words 'current-carrying conductor' and 'magnetic field'.
Marks split from a structure derived from past papers (checked twice); not Bihar Board’s official scheme
- Q3Long answer6 marksAsked: 2026
Describe the electric motor along with its principle.
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Model answer · electric motor, principle
- 1.An electric motor works on the principle of the magnetic effect of electric current. A current-carrying conductor when placed in a magnetic field experiences a force, and if the direction of the field and that of the current are mutually perpendicular to each other, then the force acting on the conductor will be perpendicular to both and will be given by Fleming's left-hand rule. This is the basis of an electric motor, which is a device that converts electric energy into mechanical energy.1 mark
- 2.When a current-carrying coil is placed in a magnetic field, a force acts on it which rotates it. In the coil ABCD, the current in arm AB flows from A to B and in arm CD it flows from C to D, opposite to the direction of current through arm AB. On applying Fleming's left hand rule for the direction of force on a current-carrying conductor in a magnetic field, the force acting on arm AB pushes it downwards while the force acting on arm CD pushes it upwards. Thus the coil and the axle, mounted free to turn about an axis, rotate anti-clockwise.1 mark
- 3.(Diagram to be drawn as described.)2 marks
- 4.The main parts of an electric motor are the armature, strong magnet, split rings, and brushes. The motor consists of a rectangular coil ABCD of insulated copper wire placed between the two poles of a magnetic field such that the arms AB and CD are perpendicular to the direction of the magnetic field. The ends of the coil are connected to the two halves P and Q of a split ring, whose inner sides are insulated and attached to an axle. The external conducting edges of P and Q touch two conducting stationary brushes X and Y.1 mark
- 5.The split ring acts as a commutator that reverses the direction of current in the coil after every half rotation. At half rotation, Q makes contact with the brush X and P with brush Y, therefore the current in the coil gets reversed and flows along the path DCBA. The reversal of current also reverses the direction of force acting on the two arms AB and CD, so the arm AB that was earlier pushed down is now pushed up and the arm CD previously pushed up is now pushed down. The reversing of the current is repeated at each half rotation, giving rise to a continuous rotation of the coil and the axle.1 mark
Diagram: Draw a rectangular coil ABCD placed between the N and S poles of a magnet, with its ends connected to the two halves P and Q of a split ring mounted on an axle; label the two stationary conducting brushes X and Y touching P and Q, show the battery connected through the brushes, and mark the arms AB and CD with arrows showing the direction of current and the directions of force on AB (downward) and CD (upward).
- State clearly that the force on the current-carrying coil is given by Fleming's left-hand rule, naming this as the basis of the motor.
- List all four parts by name in one sentence: armature, strong magnet, split rings, and brushes.
- Use the term 'commutator' when describing the split ring and explain that it reverses current after every half rotation.
Marks split from a structure derived from past papers (checked twice); not Bihar Board’s official scheme
- Q4Long answer6 marksAsked: 2023
Which type of iron is used in electromagnet and permanent magnet ? Explain the difference between both types of magnet.
How the model answer begins
1. Soft iron is used to make an electromagnet. A current-carrying solenoid can be used to magnetise a piece of magnetic material, like soft iron, when placed inside the coil, and the magnet so formed is called an…
The full answer from Medha Ma’am → - Q5Long answer6 marksAsked: 2022
Draw a labelled diagram of an electric motor. Explain its principle and working. What is the significance of the dividing ring in an electric motor?
How the model answer begins
1. A labelled diagram of an electric motor is drawn showing the rectangular coil ABCD of insulated copper wire placed between the two poles (N and S) of a magnet, with arm AB and arm CD perpendicular to the direction of…
The full answer from Medha Ma’am → - Q6Long answer6 marksAsked: 2022
Draw a labelled diagram of an electric motor. Explain its principle and working. What is the importance of split ring in an electric motor?
How the model answer begins
1. A labelled diagram of an electric motor is drawn showing the rectangular coil ABCD, the two poles (N and S) of the magnetic field, the split ring with its two halves P and Q, the conducting stationary brushes X and Y,…
The full answer from Medha Ma’am → - Q7Short answer2 marksAsked: 2021
Write the 'Right hand thumb rule' regarding magnetic effect of current.
How the model answer begins
1. The right-hand thumb rule states that if we hold a current-carrying straight conductor in our right hand such that the thumb points towards the direction of current, then this gives the direction of current along the…
The full answer from Medha Ma’am → - Q8Short answer2 marksAsked: 2021
Write two drawbacks of alternating current.
How the model answer begins
1. Alternating current at high voltage is more dangerous — its shock is more severe; it also cannot be stored directly.
The full answer from Medha Ma’am → - Q9Short answer2 marksAsked: 2025
What is dynamo? What is its use?
How the model answer begins
1. A dynamo is a device that converts mechanical energy into electrical energy. It works on the basis of electromagnetic induction, in which mechanical energy is used to rotate a conductor in a magnetic field to produce…
The full answer from Medha Ma’am → - Q10Short answer2 marksAsked: 2025
How does an electromagnet work?
How the model answer begins
1. An electromagnet is a coil of insulated copper wire wound around a soft iron core which behaves like a magnet when electric current is passed through it.
The full answer from Medha Ma’am → - Q11Short answer2 marksAsked: 2026
Make a list of two sources of magnetic field.
How the model answer begins
1. The first source of magnetic field is a permanent magnet. A permanent magnet has its own magnetic field around it, and the region surrounding a magnet, in which the force of the magnet can be detected, is said to have a…
The full answer from Medha Ma’am → - Q12Short answer2 marksAsked: 2026
What is the function of earth wire ?
How the model answer begins
1. The main function of the earth wire is to conduct any leakage current from the metallic body of electrical appliances to the earth. The metallic body is connected to the earth wire, which provides a low-resistance…
The full answer from Medha Ma’am → - Q13Short answer2 marksAsked: 2026
Write Fleming's right hand rule.
How the model answer begins
1. Fleming's right-hand rule states that we should stretch the thumb, forefinger and middle finger of right hand so that they are perpendicular to each other.
The full answer from Medha Ma’am → - Q14Short answer2 marksAsked: 2023
Why is it necessary to earth metal casing electrical appliances ?
How the model answer begins
1. Earthing metal-cased electrical appliances means connecting the metallic body of the appliance to the earth wire, which provides a low-resistance conducting path for the current. This ensures that any leakage of current…
The full answer from Medha Ma’am → - Q15Short answer2 marksAsked: 2022
State the difference between alternating current and direct current.
How the model answer begins
1. Alternating current (AC) is the current whose magnitude and direction change continuously with time. It reverses its direction periodically, that is, it changes direction after equal intervals of time.
The full answer from Medha Ma’am → - Q16Short answer2 marksAsked: 2025
What do you understand by electromagnetic induction ?
How the model answer begins
1. When there is relative motion between a coil and a magnet, the magnetic field associated with the coil changes, and due to this change an electric current is induced in the coil.
The full answer from Medha Ma’am → - Q17Short answer2 marksAsked: 2025
What is dynamo ? What is its use ?
How the model answer begins
1. A dynamo (generator) converts mechanical energy into electrical energy. It works on the basis of electromagnetic induction, that is, mechanical energy is used to rotate a conductor in a magnetic field to produce…
The full answer from Medha Ma’am →
Objective questions with the board’s key (10)
- 1. Bihar Board 2026
Dynamo converts mechanical energy into which energy ?
- (A) Sound energy
- (B) Electrical energy ✓
- (C) Solar energy
- (D) None of these
Answer: (B)
- 2. Bihar Board 2026
Direction of alternating current in a conductor
- (A) is uniform
- (B) reverses periodically ✓
- (C) changes twice
- (D) none of these
Answer: (B)
- 3. Bihar Board 2026
The value of electric current in the electric circuit at the time of overloading
- (A) decreases considerably
- (B) does not change
- (C) increases very much ✓
- (D) none of these
Answer: (C)
- 4. Bihar Board 2026
Who discovered the magnetic effect of electric current ?
- (A) Oersted ✓
- (B) Ampere
- (C) Bohr
- (D) Faraday
Answer: (A)
- 5. Bihar Board 2026
What does the middle finger of Fleming's left hand rule indicate ?
- (A) Direction of electric force applied on the conductor
- (B) Direction of electric current in the conductor ✓
- (C) Direction of the magnetic field
- (D) None of these
Answer: (B)
- 6. Bihar Board 2026
Which instrument does not have positive (+) and negative (-) signs ?
- (A) Voltmeter
- (B) An electric cell
- (C) Ammeter
- (D) Solenoid ✓
Answer: (D)
- 7. Bihar Board 2025
A horizontal magnet hanging freely in air always comes to rest in
- (A) Any direction
- (B) East-West direction
- (C) North-South direction ✓
- (D) None of these
Answer: (C)
- 8. Bihar Board 2025
If a compass is placed near a wire carrying electric current, the compass needle
- (A) Will be deflected ✓
- (B) The current carrying wire will be deflected
- (C) Will not be deflected
- (D) None of these
Answer: (A)
- 9. Bihar Board 2025
Faraday made many revolutionary discoveries, including
- (A) Electromagnetic induction
- (B) Law of electrolysis
- (C) Both (A) and (B) ✓
- (D) None of these
Answer: (C)
- 10. Bihar Board 2025
An electric motor converts
- (A) Chemical energy into electrical energy
- (B) Electrical energy into mechanical energy ✓
- (C) Mechanical energy into electrical energy
- (D) Electrical energy into chemical energy
Answer: (B)
Questions parents and students ask
- How many marks does "Magnetic Effects of Electric Current" carry in Bihar Board Class 10 Science?
- In the Bihar Board papers of 2021–2026, this chapter carried about 3 marks and about 4 questions a year; by marks it ranks 13 in Science.
- Which are the most important (VVI) questions of "Magnetic Effects of Electric Current"?
- The 17 questions above are from the board’s real papers, each with the years it was asked; the most-asked come first with their full model answers. All 17 written questions of this chapter, with answers, are in the AskMedha app.
- Do the answers follow the board’s marking scheme?
- BSEB does not publish a marking scheme. Each answer is written point by point on a structure derived from past papers and checked by a second, independent model; it is never called the board’s official scheme.
The same preparation, with Medha Ma’am — on your phone
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