Question

For a circular coil carrying current, the thumb in the right hand thumb rule gives the direction of

• A. magnetic field
• B. current
• C. induced emf
• D. electric field
• E. electric force

Hint:

Right hand thumb rule: thumb → current direction (straight wire), curled fingers → magnetic field. For coils, thumb gives magnetic field direction.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The right-hand thumb rule (also known as the right-hand grip rule) is a mnemonic used to determine the direction of the magnetic field produced by a current-carrying conductor. The application of the rule is slightly different for a straight wire versus a circular loop. This question specifies a circular coil.
Step 2: Key Formula or Approach:
Right-Hand Thumb Rule for a Circular Coil/Loop:
If you curl the fingers of your right hand in the direction of the electric current flowing through the circular coil, your outstretched thumb will point in the direction of the magnetic field inside the loop (particularly at its center).
Step 3: Detailed Explanation:
The question describes the use of the right-hand thumb rule for a circular current-carrying coil. Following the rule stated above:
- The curled fingers represent the direction of the current (\(I\)).
- The thumb represents the direction of the magnetic field (\( \vec{B} \)) produced by this current.
Therefore, the thumb indicates the direction of the magnetic field.
Induced emf, electric field, and electric force are related but different concepts, and their directions are determined by other rules (like Faraday's Law or Lorentz force law).
Step 4: Final Answer:
For a circular coil, the thumb in the right-hand thumb rule gives the direction of the magnetic field. This corresponds to option (A).