Which has greater resistance $\mathit{1} \mathrm{kW}$ electric heater or a $\mathit{100} \mathrm{W}$ filament bulb both marked for $\mathit{220} \mathrm{V}$?

 A wire of uniform area of cross section is stretched to four times its original length. What factor does its resistivity change?

 Why resistance become less in parallel combination?

A wire of resistance $20$ohm is bent in the form of a closed circle. What is the effective resistance between the two points at the ends of any diameter of the circle?

Define resistivity. How does it vary If:

(i) Length is doubled (ii) Area is halved (iii) Length and area are doubled (iv) Area is doubled.

An electric bulb is marked $\mathit{100} \mathrm{W}, \mathit{230} \mathrm{V}.$ What is the energy produced by the bulb in $\mathit{20}$ minutes when operated at $\mathit{230} \mathrm{V}$?

How many electrons are there in one coulomb of charge?

Why is Tungsten used almost exclusively for filament of incandescent lamps?

Why is an ammeter likely to be burnt out if you connect it in parallel?