NEETPhysicsMagnetic Effects of Current
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): For a long straight solid cylinder carrying a uniform current, the magnitude of the magnetic field is maximum at its surface. Reason (R): The magnetic field inside the cylinder increases linearly with distance from the axis, and outside the cylinder it decreases inversely with distance. In the ligh
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
Step-by-step solution
For a long straight solid cylinder of radius R carrying uniform current I , the magnetic field at a distance r from the axis is given by: Inside ( r Outside ( r > R ): B = ₀ I 2 r B 1 r Thus, the magnetic field increases linearly from the axis to the surface, reaches a maximum at the surface ( r = R ), and then decreases inversely with distance outside. Therefore, both Assertion (A) and Reason (R) are true, and (R) correctly explains why the maximum is at the surface. Answer: Both (A) and (R) are correct and (R) is