Question

The magnetic field at a distance of 10 cm from a long straight thin wire carrying a current of 4 A is

• A. 6 \(\mu\)T
• B. 16 \(\mu\)T
• C. 8 \(\mu\)T
• D. 4 \(\mu\)T

Hint:

Use the formula \( B = \frac{\mu_0 I}{2 \pi r} \) to find magnetic field around a current carrying wire.

Answer 1

The Correct Option is C

Step 1: Use Biot-Savart Law formula
Magnetic field \( B \) at distance \( r \) from a long straight wire carrying current \( I \): \[ B = \frac{\mu_0 I}{2 \pi r} \] where \(\mu_0 = 4 \pi \times 10^{-7} \, T \cdot m/A\).
Step 2: Substitute values
\[ I = 4\, A, \quad r = 10\, cm = 0.1\, m \] \[ B = \frac{4 \pi \times 10^{-7} \times 4}{2 \pi \times 0.1} = \frac{16 \pi \times 10^{-7}}{0.2 \pi} = 8 \times 10^{-6} \, T = 8\, \mu T \] Step 3: Conclusion
The magnetic field is \(8\, \mu T\).