The terminals of a 070 V watch battery are connected by a 90

The terminals of a 0.70 V watch battery are connected by a 90.0-m-long gold wire with a diameter of 0.100 mm. Part A What is the current in the wire? Express your answer using three significant figures.

Solution

V = 0.70

R = rho*L/A

rho of gold = 2.44*10^-8 ohm.m

Area = pi*d^2/4 = pi*r^

R = 2.44*10^-8*90/(3.14*0.05^2*10^-6) = 279.74 ohm

ohm\'s law

V = IR

I = V/R = 0.7/279.74 = 2.5*10^-3 Amp.

I = 2.50 mA