The temperature coefficient of resistivity of material is 0.0004/k. When the temperature of the material is increased by `50^(@)C`, its resistivity increases by `2xx10^(-8)` ohm-m. The initial resistivity of the material in ohm-m is 

Explanation

`t_2 - t_1 = 50^@ C, rho_2 - rho_1 = 2 xx 10^(-8) Omega -m`
`alpha = 0.00004 K^(-1)`. Initial Resistivity `rho_1` = ?
`alpha =((rho_2 - rho_1)//rho_1)/((t_2- t_1))`
`therefore rho = ((rho_2 - rho_1))/(alpha (t_2 - t_1)) = (2xx10^(-8))/(0.00004 xx 50)`
`= 1000xx10^(-8) Omega - m`