A straight wire of diameter 1 mm carrying a current of 2 amperes is replaced by another wire of 2 mm diameter. the strength of the magnetic field far away is

Options

A. twice the earlier value
B. one half the earlier value
C. one quarter the earlier value
D. same as the earlier value

Explanation

To solve the problem, we need to understand how the magnetic field produced by a straight current-carrying wire is determined. The magnetic field (B) at a distance (R) from a long straight wire carrying a current (I) is given by the formula:

\[ B = \frac{\mu_0 I}{2 \pi R} \]

Where:
- \( B \) is the magnetic field strength,
- \( \mu_0 \) is the permeability of free space (a constant),
- \( I \) is the current in amperes,
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