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Q1. A circular coil produces maximum magnetic field at its:
A circular coil produces the maximum magnetic field at its centre. The magnetic field lines from all parts of the loop contribute at the centre in the same direction, adding up to give the strongest field. The field decreases as we move away from the centre.
Q2. Soft iron placed inside a current-carrying solenoid becomes:
Soft iron placed inside a current-carrying solenoid becomes an electromagnet. The soft iron core intensifies the magnetic field and becomes magnetized as long as current flows. When the current stops, it loses its magnetism. This is the principle of an electromagnet.
Q3. The right-hand thumb rule is applicable to:
The right-hand thumb rule is applicable to current-carrying conductors. It is used to find the direction of the magnetic field around a straight current-carrying wire, a circular loop, or a solenoid. The thumb points in the direction of current, and the curled fingers show the direction of the magnetic field.
Q4. When current flows from B to A, the rod is displaced towards the:
Q5. In the right-hand thumb rule, the curled fingers show the direction of:
In the right-hand thumb rule, the curled fingers show the direction of the magnetic field lines around the conductor. The thumb points in the direction of the current. This rule helps visualize the circular magnetic field around a straight conductor.
Q6. In the right-hand thumb rule, the thumb points in the direction of:
In the right-hand thumb rule, the thumb points in the direction of the electric current. The curled fingers then indicate the direction of the magnetic field lines around the conductor.
Q7. For the same power line, the magnetic field above the wire is directed from:
Q8. Magnetic field produced by a given current decreases as the:
The magnetic field produced by a given current decreases as the distance from the conductor increases. The field strength is inversely proportional to the distance from the wire (B ∝ 1/r).
Q9. If a circular coil has n turns, the magnetic field produced is:
If a circular coil has n turns, the magnetic field produced is n times that of a single turn. Each turn contributes equally to the field at the centre, so the total field is proportional to the number of turns.
Q10. A solenoid is a coil of many turns wound in the shape of a:
A solenoid is a coil of many turns wound in the shape of a cylinder. It is like a helical coil that produces a strong, uniform magnetic field inside it when current flows.
Q11. Parallel field lines inside a solenoid indicate that the magnetic field is:
Parallel field lines inside a solenoid indicate that the magnetic field is uniform. This means the field strength and direction are the same at all points inside the solenoid. This is a unique property of solenoids.
Q12. A solenoid produces a strong magnetic field inside it when:
A solenoid produces a strong magnetic field inside it when current flows through it. The field is strong and uniform inside the solenoid, similar to that of a bar magnet.
Q13. Which rule is used to find the direction of force on a current-carrying conductor placed in a magnetic field?
Fleming’s left-hand rule is used to find the direction of force on a current-carrying conductor placed in a magnetic field. The thumb, forefinger, and middle finger are held mutually perpendicular. The forefinger points in the direction of the field, the middle finger in the direction of current, and the thumb gives the direction of force.
Q14. The force on a current-carrying conductor depends on the:
The force on a current-carrying conductor depends on the current (I), the magnetic field strength (B), and the direction of current (angle between current and field). The force is given by F = BIL sin θ.
Q15. As we move away from a straight current-carrying wire, the concentric magnetic field circles become:
As we move away from a straight current-carrying wire, the concentric magnetic field circles become larger. The field strength decreases with distance, and the circles spread out.
Q16. A magnetic field exerts force on a nearby:
A magnetic field exerts force on a nearby magnet. It also exerts force on a current-carrying conductor. Switches, batteries, and resistors do not experience magnetic force directly unless current flows through them.
Q17. Magnetic force on a conductor is perpendicular to:
Magnetic force on a conductor is perpendicular to both the magnetic field and the current. According to Fleming’s left-hand rule, the force is perpendicular to the plane containing the current and the magnetic field.
Q18. Which rule helps to find the direction of magnetic field around a straight conductor?
The right-hand thumb rule helps to find the direction of the magnetic field around a straight current-carrying conductor. The thumb points in the direction of current, and the curled fingers give the direction of the magnetic field lines.
Q19. Iron filings sprinkled near a current-carrying coil show:
Iron filings sprinkled near a current-carrying coil show the magnetic field pattern. The filings align themselves along the magnetic field lines, revealing the shape and direction of the field.
Q20. When either current or magnetic field is zero, the force on the conductor is:
When either current or magnetic field is zero, the force on the conductor is zero. The force is given by F = BIL sin θ, so if B = 0 or I = 0, F = 0.
Q21. Increasing current in the conductor increases the force acting on it because magnetic field:
Increasing current in the conductor increases the magnetic field around it. Since the force depends on the magnetic field (F = BIL), the force also increases.
Q22. The combined study of current, magnetic field and force leads to the development of:
The combined study of current, magnetic field, and force leads to the development of electromagnetic devices like electric motors, generators, speakers, and many other devices that use the interaction between electricity and magnetism.
Q23. The direction of force changes when the direction of current is:
The direction of force changes when the direction of current is reversed. According to Fleming’s left-hand rule, reversing the current reverses the direction of the force on the conductor.
Q24. Magnetic field at a point depends directly on the:
The magnetic field at a point depends directly on the current. A larger current produces a stronger magnetic field. The field also depends on the distance and the shape of the conductor.
Q25. A horizontal power line carries current from east to west. Below the wire, the magnetic field is directed from:
Using the right-hand thumb rule, if current flows from east to west (thumb pointing west), below the wire the magnetic field curls from south to north. Above the wire, it would be from north to south.
Q26. An electromagnet works only when:
An electromagnet works only when current flows through it. When current flows, the core becomes magnetized. When the current stops, the magnetism disappears. This is the key difference between an electromagnet and a permanent magnet.
Q27. The magnetic field inside a solenoid is uniform because field lines are:
The magnetic field inside a solenoid is uniform because the field lines are parallel and equally spaced. This means the field has the same strength and direction at all points inside the solenoid.
Q28. Each small section of a circular loop contributes magnetic field at the centre in:
Each small section of a circular loop contributes to the magnetic field at the centre in the same direction. This is why the fields from all sections add up, producing a strong field at the centre.
Q29. The aluminium rod is placed between the poles of a:
In the activity demonstrating the force on a current-carrying conductor, the aluminium rod is placed between the poles of a horseshoe magnet. The horseshoe magnet provides a strong, uniform magnetic field.
Q30. What is the device that converts electrical energy into mechanical energy using the magnetic effect of current?
An electric motor converts electrical energy into mechanical energy using the magnetic effect of current. The current-carrying coil experiences a force in a magnetic field, causing it to rotate. This is based on Fleming’s left-hand rule.
Q31. The force on a current-carrying conductor is due to interaction between:
The force on a current-carrying conductor is due to the interaction between the magnetic field produced by the current and the external magnetic field. This interaction creates a mechanical force on the conductor.
Q32. A uniform magnetic field is represented by field lines that are:
A uniform magnetic field is represented by field lines that are equally spaced and parallel. This means the field strength is the same at all points, and the direction is constant. An example is the field inside a solenoid.
Q33. Displacement of the rod shows that a magnetic field exerts a:
Displacement of the rod shows that a magnetic field exerts a mechanical force on a current-carrying conductor. This is the principle behind electric motors and many other electromagnetic devices.
Q34. The magnitude of magnetic field at a point increases when the current through the wire:
The magnitude of the magnetic field at a point increases when the current through the wire increases. The field is directly proportional to the current (B ∝ I).
Q35. Andre Marie Ampere suggested that a magnet exerts force on a:
Andre Marie Ampere suggested that a magnet exerts force on a current-carrying conductor. He also proposed that two parallel current-carrying conductors exert forces on each other, which is the basis of the definition of the ampere.
Q36. The rod moves because charges inside it experience:
The rod moves because charges (electrons) inside it experience a magnetic force when current flows through the rod placed in a magnetic field. This force is given by F = qvB.
Q37. What is the effect on the force experienced by a current-carrying conductor in a magnetic field if the current is increased?
If the current is increased, the force experienced by the current-carrying conductor in a magnetic field increases. The force is directly proportional to the current (F = BIL).
Q38. Reversing the direction of current causes the rod to move towards the:
Reversing the direction of current causes the rod to move in the opposite direction. This is because the force is given by F = BIL, and reversing I reverses the direction of the force.
Q39. The phenomenon of force on current-carrying conductor was explained by:
The phenomenon of force on a current-carrying conductor was explained by Andre Marie Ampere. He showed that a current-carrying conductor experiences a force when placed in a magnetic field.
Q40. Field due to each turn of a coil adds up because current flows in:
The field due to each turn of a coil adds up because current flows in the same direction through all turns. This means the magnetic fields produced by each turn add together, making the total field stronger.
Q41. The magnetic field pattern of a solenoid is similar to that of a:
The magnetic field pattern of a solenoid is similar to that of a bar magnet. One end of the solenoid behaves like a north pole, and the other end behaves like a south pole. The field lines inside are uniform and parallel.
Q42. The magnetic field around a straight conductor depends inversely on:
The magnetic field around a straight conductor depends inversely on the distance from the conductor (B ∝ 1/r). This means the field is stronger closer to the wire and weaker farther away.
Q43. One end of a current-carrying solenoid behaves as:
One end of a current-carrying solenoid behaves as a north pole, and the other end behaves as a south pole. The end where the current flows in an anticlockwise direction (when viewed from that end) is the north pole.
Q44. The magnetic field produced by a straight wire becomes weaker when:
The magnetic field produced by a straight wire becomes weaker when the distance from the wire increases. The field strength is inversely proportional to the distance (B ∝ 1/r).
Q45. When the compass is moved farther from the current-carrying wire, the needle deflection:
When the compass is moved farther from the current-carrying wire, the needle deflection decreases. This is because the magnetic field strength decreases with distance, so the compass needle experiences a weaker force.
Q46. Inside a solenoid, the magnetic field lines are:
Inside a solenoid, the magnetic field lines are parallel and straight. This indicates that the magnetic field is uniform inside the solenoid. The field lines are equally spaced and have the same direction.
Q47. Magnetic field inside a circular loop is due to:
The magnetic field inside a circular loop is due to the contribution of all wire segments. Each small segment of the loop produces a magnetic field at the centre, and all these fields add up in the same direction.
Q48. The interaction between magnetic field and current leads to:
The interaction between a magnetic field and a current leads to motion. This is the principle behind electric motors—the magnetic field exerts a force on the current-carrying conductor, causing it to move.
Q49. When a straight wire is bent into a circular loop, the magnetic field pattern:
When a straight wire is bent into a circular loop, the magnetic field pattern changes in shape. Instead of circular lines around a straight wire, the field lines become more concentrated at the centre of the loop.
Q50. At the centre of a current-carrying circular loop, the magnetic field lines appear:
At the centre of a current-carrying circular loop, the magnetic field lines appear straight (perpendicular to the plane of the loop). The field at the centre is along the axis of the loop and is the strongest at that point.