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: Formula
$B = \mu_0\mu_r\,nI$ for a solenoid filled with a medium of relative permeability $\mu_r$.

Step 2: Read the dependence
$n$, $I$ and $\mu$ appear, while the wire radius and the solenoid radius do not.

Step 3: Match
So the list is (a), (c) and (d).

Step 4: Check
Options (A) and (B) include (b), which is not in the formula, and (C) leaves out (a), which is.

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