A nichrome wire 50 cm long and one square millimetre cross- section carries a current of 4 A when connected to a 2 V battery. The resistivity of nichrome wire in ohm metre is

Options

A. `1 xx 10^(-6)`
B. `4 xx 10^(-7)`
C. `3 xx 10^(-7)`
D. `2 xx 10^(-7)`

Answer

A

Explanation

`I =0.5 m, A = 1 xx 10^(-6) m^(2), I = 4A,V = 2V`
`R = (rho l)/A rArr 2/4 = rho xx 0.5/10^(-6) rArr rho = 10^(-6) Omega m`