Question

calculate the resistance of a 5m length of a wire of area of cross section 0.01 mm square and resistivity 50 into 10 raised to -8ohm metre

Answer 1

millimeter = 10⁻³ m

R = ρ L / A
   = 50 * 10⁻⁸ Ohm-m * 5 m / [ 0.01 * 10⁻³ * 10⁻³  m² ]
   = 250 Ohms
 

Answer 2

Answer:

R= rho× L/

=(50×10^-8) × 5/ (.01×10^-6)

because area is given in millimeter square. So ((10^-3)².

So, R= (250×10^-8) / (.01×10^-6)

R= 25000×10^-2=250 ohm