Question

Draw magnetic field lines showing the direction of the magnetic field due to a current carrying long straight solenoid. State the conclusion which can be drawn from the pattern of magnetic field lines inside the solenoid. Name any two factors on which the magnitude of the magnetic field due to this solenoid depends.

Answer 1

Cnoclusion:

• Inside the solenoid: The field lines are parallel and evenly spaced, indicating a uniform magnetic field similar to that of a bar magnet.
• Outside the solenoid: The field lines form closed loops, showing that the solenoid behaves like a magnet with a north and south pole.
• Stronger field inside: The field is stronger inside the solenoid and weaker outside.

Factors:

1. Current (I): The strength of the magnetic field is directly proportional to the current passing through the solenoid. A higher current produces a stronger magnetic field.
2. Number of turns per unit length (n): The magnetic field strength is directly proportional to the number of turns of wire per unit length of the solenoid. More turns of wire in a given length result in a stronger magnetic field.

Answer 2

Conclusion:

The magnetic field is concentrated into a nearly uniform region at the center of a long solenoid. The magnetic field outside is weakened, and the field lines are more widely spaced.

Factors:

1. Number of turns per unit length of the solenoid.
2. The strength of the current flowing through the solenoid.