A wire has a diameter of 0.5 mm and a resistivity of 1.6 × 10−6 ohm cm. How much of this wire would be required to make a 10 ohm coil?
A copper wire has a diameter of 1 mm and reistivity 1.6 x 10 -6 ohm m. How much of this wire would be necessary to make a 20 ohm coil?