Q12 of 41 Page 461

The resistivity of copper is 1.7 × 10-8 Ωm. What length of copper wire of diameter 0.1 mm will have a resistance of 34Ω?

Given

Resistivity (ρ) = 1.7 × 10-8 Ωm


Diameter (d) = 0.1 mm = 0.1×10-3 m


(∵ 1m = 1000 mm)


Resistance(R) = 34 Ω


Area of cross section (A) =


A =


⇒ A =


Now



⇒


⇒


⇒


⇒


Hence the length of the wire is 15.7 m.


More from this chapter

All 41 →
10

A 9 Ω resistance is cut into three equal parts and connected in parallel. Find the equivalent resistance of the combination.

 11

An electrical appliance draws a current of 0.5 A when applied potential difference across it is 220V. Calculate the amount of charge flowing through it in 30 minutes.

 13

Draw a schematic diagram of an electric circuit consisting of battery of five 2V cells, a 20 Ω resistor, a 30 Ω resistor, a plug key, all connected in series. Calculate the value of current flowing through the 20 Ω resistor and the power consumed by the 30 Ω resistor.

 14

What do the following circuit symbols represent?