A nichrome wire 50 cm long and one square millimeter cross-section carries a current of 4A when connected to a 2V battery. The resistivity of nichrome wire in ohm meter is:
Correct answer: A. 1 x 10^-6
- A. 1 x 10^-6
- B. 4 x 10^-7
- C. 3 x 10^-7
- D. 2 x 10^-7
Explanation
l = 50cm = 0.5m and A = 1m × m2 =10-6 m2 . As R=V/i=ρl/A → ρ=VA/li = 4 × 0.52 × 10-6 = 10-6 Ω - m = 1 × 10-6 Ω - m. Hence, this option is correct.
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