Embibe Experts Solutions for Exercise 1: ICSE-2018

The order of coloured rings in a carbon resistor is red, yellow, blue and silver. The resistance of the carbon resistor is :

Define current density. Write an expression which connects current density with drift speed.

 An electric bulb is marked 200 V, 100 W. Calculate electrical resistance of its filament. If five such bulbs are connected in series to a 200 V supply, how much current will flow through them ?

A metallic wire having a resistance of $20 \Omega$ is bent in order to form a complete circle. Calculate the resistance between any two diametrically opposite points on the circle.

A uniform copper wire having a cross-sectional area of $1 {\mathrm{mm}}^2$ carries a current of $5 \mathrm{A}$. Calculate the drift speed of free electrons in it. (Free-electron number density of copper$=2\times {10}^{28}/{\mathrm{m}}^3$)

An electric bulb is rated as $250 \mathrm{V}, 750 \mathrm{W}$. Calculate the electric current flowing through it, when it is operated on a $250 \mathrm{V}$ supply. 

An electric bulb is rated as $250 \mathrm{V}, 750 \mathrm{W}$. Calculate the resistance of its filament.