CLASS 10 SCIENCE – HOTS QUESTIONS
Magnetic Effects of Electric Current
Higher Order Thinking Skills (HOTS)
Note: Questions are based on the Class 10 NCERT concepts of magnetic field, field lines, straight conductors, circular coils and solenoids. Electric Motor and Electric Generator are excluded.
1. A compass is placed near a straight current-carrying conductor. When the direction of current is reversed, the compass needle deflects in the opposite direction. Explain why this happens using the Right-Hand Thumb Rule.
2. Two students make electromagnets using identical iron nails and equal-length insulated copper wires. Electromagnet A has 20 turns, while B has 40 turns, with the same current flowing through both. Which electromagnet will be stronger? Give a reason.
3. A current-carrying straight conductor produces a magnetic field around it. What will happen to the strength of the magnetic field at a particular point if the current is doubled and the distance from the conductor is also doubled? Explain your reasoning.
4. A student observes that the magnetic field lines around a current-carrying straight conductor become closer together when the current is increased. What does this observation tell us about the relationship between current and magnetic field strength?
5. A circular coil carrying current produces a magnetic field. If the direction of current through the coil is reversed, what changes will occur at the centre of the coil? Explain using the Right-Hand Thumb Rule.
6. Two circular coils have the same number of turns and carry the same current. Coil A has a smaller radius than Coil B. Which coil will produce a stronger magnetic field at its centre? Explain.
7. A solenoid is connected to a battery and behaves like a bar magnet. If the battery terminals are interchanged, what happens to the north and south poles of the solenoid? Give a scientific reason.
8. A student says, “Magnetic field lines can intersect because they are only imaginary lines.” Do you agree? Explain why magnetic field lines cannot intersect.
9. An electromagnet is required to lift a heavier load without changing the core material. Suggest two changes that can increase its strength and explain the scientific basis of each.
10. A current-carrying conductor is placed near a compass. The compass shows no deflection, even though current is flowing through the conductor. Does this necessarily mean that there is no magnetic field? Give one possible explanation based on the direction/arrangement of the conductor and magnetic field.
Magnetic Effects of Electric Current
1. Reversing the current reverses the direction of the magnetic field around the conductor. Hence, the compass needle deflects in the opposite direction.
2. Electromagnet B will be stronger because the strength of a solenoid increases with the number of turns, when current is the same.
3. The magnetic field strength will remain approximately the same, because \(B \propto \frac{I}{r}\). Doubling both current and distance gives the same ratio.
4. Closer field lines indicate a stronger magnetic field. Thus, magnetic field strength increases with current.
5. The direction of the magnetic field reverses. Therefore, the north and south poles of the coil interchange.
6. Coil A will produce a stronger magnetic field because the magnetic field at the centre of a circular coil increases as its radius decreases.
7. The north and south poles interchange because reversing the battery reverses the direction of current through the solenoid.
8. No. Magnetic field lines cannot intersect because at the point of intersection, a compass would have to show two different directions of the magnetic field.
9.
- Increase the number of turns of the coil.
- Increase the current through the coil.
Both increase the strength of the electromagnet.
10. No. The magnetic field may be present, but the conductor may be arranged such that its magnetic field produces little or no deflection at the compass, or the compass may be positioned where the field effect is not appreciable.