R P Goyal and S P Tripathi Solutions for Chapter: Electrical Power and Household Circuits, Exercise 1: EXERCISE-9(A)

Distinguish between kilowatt and kilowatt-hour.

List the names of three electrical gadgets used in your house. Write their power, voltage rating and approximate time for which each one is used in a day. Hence find the electrical energy consumed by each in a day.

A battery of e.m.f. $15 \mathrm{V}$ and internal resistance $2 \mathrm{\Omega }$ is connected to two resistors of resistances $4$ ohm and $6$ ohm joined in series. Find the electrical energy spent per minute in $6$ ohm resistor.

Water in an electric kettle connected to a $220 \mathrm{V}$ supply takes $5$ minutes to reach its boiling point. How long will it take if the supply voltage falls to $200 \mathrm{V}$?

An electric toaster draws current $8 \mathrm{A}$ in a circuit with source of voltage $220 \mathrm{V}$. It is used for $2 \mathrm{h}$. Find the cost of operating the toaster if the cost of electrical energy is ₹ $4.50$ per $\mathrm{kWh}$.

An electric kettle is rated $2.5 \mathrm{kW},250 \mathrm{V}.$ Find the cost of running the kettle for two hours at $₹ 5.40$ per unit.

A geyser is rated '$1500 \mathrm{W}, 250 \mathrm{V}$'. This geyser is connected to $250 \mathrm{V}$ mains. Calculate the current drawn.

A geyser is rated '$1500 \mathrm{W}, 250 \mathrm{V}$'. This geyser is connected to $250 \mathrm{V}$ mains. Calculate:
(i) The energy consumed in $50$ hours.
(ii) The cost of energy consumed at ₹ $4.20$ per $\mathrm{kWh}$.