Question

(a) Give two examples of substances which are good conductors of electricity. Why do you think they are good conductors of electricity?
(b) Calculate the resistance of a copper wire 1.0 km long and 0.50 mm diameter if the resistivity of copper is 1.7 × 10−8 Ω m.

Answer 1

Answer:

a) copper and silver because they both have high melting and boiling point and they are good conductors of electricity .

b) -------

Answer 2

(a) Two examples of substances which are good conductors of electricity are Copper and Gold.

(b) The resistance of the copper wire is 86.6 ohm .

Explanation:

(a) Conductors are the components which allow the current to flow in one direction.

Two examples of substances which are good conductors of electricity are Copper and Gold.

The electric charges present in the atomic structure of the metal flows through freely and copper being the less expensive and gold possessing higher corrosion resistance makes the good conductors of electricity.

(b) According to the question,

Length of the copper wire = 1 km.

Diameter, d= 0.50 mm and resistivity,   ρ= 1.7 x 10-8 Ωm

From diameter, we get, radius, $r= \frac{d}{2} = \frac{(0.50 mm)}{2} = 0.25mm = 0.25 \times 10^{-3} m.$

Now,

R = ρl/A

  = ρl/πr²

  = $\frac{(1.7 \times 10^{-8} \Ohms \times 1000 )}{(3.14 \times (0.25 \times 10^{-3}) ^{2}}$

  = 86.6 Ω

Hence, the resistance of the copper wire is 86.6 ohm