What is the equivalent resistance of resistors $R_{1}$ and $R_{2}$ connected in parallel connection?
$\frac{1}{R_{1}}+\frac{1}{R_{2}}$
$\frac{R_{1}+R_{2}}{R_{1} R_{2}}$
$\frac{R_{1} R_{2}}{R_{1}+R_{2}}$
$\frac{R_{1}+R_{2}}{2}$
$(a)$ What material is used in making the filament of an electric bulb ?
$(b)$ Name the characteristics which make it suitable for this.
The equivalent resistance in series combination is
An electric appliance draws a current of $0.4\, A$ when the voltage is $200$ volt. Calculate the amount of charge flowing through it in one hour.
The resistivity does not change if
Give an example of a metal which is the best conductor of heat.