Narendra Kumar Solutions for Chapter: Electricity, Exercise 6: PROBLEMS FOR PRACTICE

An electric bulb is rated at $250 \mathrm{V}$, $100 \mathrm{W}$. What is its resistance? What maximum current can be passed through it?

Two bulbs are marked $60 \mathrm{W}$, $220 \mathrm{V}$ and $60 \mathrm{W}$, $110 \mathrm{V}$ respectively. Calculate the ratio of their resistances.

A bulb marked $10 \mathrm{V}$, $40 \mathrm{W}$ operates on a $10$ volt battery for $5$ minutes. Calculate the current flowing through it.

A bulb marked $10 \mathrm{V}$, $40 \mathrm{W}$ operates on a $10 V$  battery for $5$ minutes. Calculate the energy liberated.

An electric kettle is rated $1.5 \mathrm{kW}$, $250 \mathrm{V}$. Find the cost of running the kettle for $3$ hours at $\mathrm{Rs}. 2.50$ per unit.

Three equal resistances connected in series take $10 \mathrm{W}$ power from the main supply. If these resistances be connected in parallel, then how much power will they take?

Water in an electric kettle connected to a $240 \mathrm{V}$ supply took $4$ minutes to reach its boiling point. How long would it have taken if the supply had been of $200 \mathrm{V}$?

Two bulbs $A$ and $B$ are rated $100 \mathrm{W}$, $120 \mathrm{V}$ and $10 \mathrm{W},$ $120 \mathrm{V}$ respectively. They are connected in series across a $120 \mathrm{V}$ source. Find the current in each bulb. Which bulb will consume more power?