Question

The magnetic induction produced inside an ideal solenoid, depends on which of the following quantities ?
(a) number of turns per unit length.
(b) radius of the wire.
(c) current flowing throught it.
(d) permeability of the medium.

• A. (a), (b) and (d)
• B. (a), (b) and (c)
• C. (b), (c) and (d)
• D. (a), (c) and (d)

Hint:

Inside an ideal solenoid B = mu n I, so it depends on n, I and the medium.

Answer 1

The Correct Option is D

Step 1: Understand the concept
Inside a long ideal solenoid, the field is uniform and equals \(B = \mu\,n\,I\), where \(n\) is the number of turns per unit length, \(I\) is the current and \(\mu\) is the permeability of the medium inside.

Step 2: Match the quantities
(a) the number of turns per unit length, \(n\), appears directly. (c) the current \(I\) appears directly. (d) the permeability \(\mu\) of the medium appears directly.

Step 3: Radius of the wire
(b) The radius of the wire does not appear in the formula. The field depends on the current and the turns per unit length, not on the thickness of the wire.

Step 4: Result
The field depends on (a), (c) and (d), option (D).

Final Answer:
The field depends on turns per unit length, current and permeability. This is option (D). \[ \boxed{\text{(D) }\text{(a), (c) and (d)}} \]