Question

The magnetic field inside the solenoid is

• A. directly proportional to its length.
• B. directly proportional to current
• C. inversely proportional to current
• D. inversely proportional to total number of turns

Hint:

The field inside a long solenoid is B equals mu zero n I.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
For a long solenoid, \(B=\mu_{0}nI\), where \(n\) is the number of turns per unit length.

Step 2: Check the dependence
\(B\) is directly proportional to the current \(I\). It increases with the number of turns, and for a fixed number of turns it decreases as the length increases.

Step 3: Compare the options
Only the statement that \(B\) is directly proportional to the current is correct.

Final Answer:
The field inside a solenoid is directly proportional to the current. \[ \boxed{\text{(B) }\text{directly proportional to current}} \]