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

Use
\[I = \frac{V}{R}\]
\[Resistance=\frac{(resistivity)(length \space of \space wire( m))}{Area \space of \space crossection}\]
And find out yourself

Answer 2

Make sure you write all the quantities in SI units