Question

A 20-cm long and 1.0-mm diameter thick copper wire (resistivity 1.7 × 10-8 Ωm) is connected across a 3-V battery. The current through the wire is

Answer 1

Could someone explain. I am having a very hard time with physics. I know this may be simple to a lot of people but I'm lost.

Answer 2

We know from Ohm's law, that current is
\[I=\frac{V}{R}\]
we have v voltage given as 3 volts
we need to find R resistance
We know
\[R=\rho \frac l A\]
" 20-cm long and 1.0-mm diameter thick copper wire (resistivity 1.7 × 10-8 Ωm)"
length= 20 cm or 20 x10^(-2) meters
Area=
\[\pi r^2\]
We have diameter as 1 mm so radius 0.5 mm
\[A=\pi r^2=\pi (0.5\times 10^{-3})^2\]
Resistivity \(\rho\) is given
\[\rho=1.7 \times 10^{-8}\]

Answer 3

First find resistance , then you can find current.

Let me know if you have any trouble