B M Sharma Solutions for Chapter: Heating Effects of Current, Exercise 4: Archives

Two electric bulbs marked $25 \mathrm{W}-220 \mathrm{V}$ and $100 \mathrm{W}-220 \mathrm{V}$ are connected in series to a $440 \mathrm{V}$ supply. Which of the bulbs will fuse?

The supply voltage to a room is $120 \mathrm{V}$. The resistance of the lead wires is $6 \mathrm{\Omega }$. A $60 \mathrm{W}$ bulb is already switched on. What is the decrease of voltage across the bulb, when a $240 \mathrm{W}$ heater is switched on in parallel to the bulb?

In a large building, there are $15$ bulbs of $40 \mathrm{W}$, $5$ bulbs of $100 \mathrm{W}$, $5$ fans of $80 \mathrm{W}$ and $1$ heater of $1 \mathrm{kW}$. The voltage of the electric mains is $220 \mathrm{V}$. The minimum capacity of the main fuse of the building will be

Incandescent bulbs are designed by keeping in mind that the resistance of the filament increases with the increase in temperature. If at room temperature, $100 \mathrm{W}, 60 \mathrm{W},$ and $40 \mathrm{W}$ bulbs have filament resistances $R_{100}, R_{60},$ and $R_{40},$ respectively, the relation between these resistances is

For the circuit shown in the figure,

The heater of an electric kettle is made of a wire of length $L$ and diameter $d$. It takes $4 \mathrm{minutes}$ to raise the temperature of $0.5 \mathrm{kg}$ water by $40 \mathrm{K}$. This heater is replaced by a new heater having two wires of the same material, each of length $L$ and diameter $2d$. The way these wires are connected is given in the options. How much time in minutes will it take to raise the temperature of the same amount of water by $40 \mathrm{K}$?