Find the voltage drop (in mv) across an 46.6 m long copper wire with diameter of 1.11 mm and with 47.6 miliamps of current running through it. (the resistivity of copper at room temperature is 1.68×10-8 ohm×meter). express the answer (only numerical value) to the nearest whole number.

First we need to calculate the resistance of this piece of wire. For a wire with resistivity , length L and cross section A, the resistance is

The diameter d of the wire is , so the cross sectional area is

Now, using  and , we can calculate the resistance:


And now we can calculate the voltage drop across the resistor, by using Ohm's law, since we know the current flowing through it: 

Show him another sport or something