Dr. Sunil Kushwaha Solutions for Chapter: Electricity, Exercise 8: Numericals for Practice

In a house four $60 \mathrm{W}$electric bulbs are lighted for $2$ hours and two $100 \mathrm{W}$ bulbs are lighted for $4$ hour everyday. Calculate the energy consumed in the house for $30$ days.

An electric bulb draws a current of $0.8 \mathrm{A}$ and works on $250 \mathrm{V}$ on the average $8$ hours a day. If energy costs $\mathrm{Rs}. 3$ per $\mathrm{kWh}$, calculate monthly bill for $30$ days.

How should the two resistance of $2 \mathrm{ohms}$ be connected so as to produce equivalent resistance of $1 \mathrm{ohm}$?

In a domestic circuit five $40 \mathrm{W}$ bulbs are used for $3$hours and one $100 \mathrm{W}$ bulb is used for $1$ hour daily. There are three TV sets each of $50 \mathrm{W}$ and they are used $10$ hours daily. Calculate the energy consumed in a month. Also find the total cost when the charge of one unit energy is $₹ 3.50$.

Two identical resistors, each of resistance $4 \mathrm{\Omega }$ are connected in turn (i) in series.(ii) in parallel, to a battery of $12$volt. Calculate the ratio of power consumed in the two cases.

Calculate the resistance of $100\mathrm{m}$ long copper wire having area of cross-section $0.01 {\mathrm{mm}}^2$  and resistivity $5.0\times {10}^{-8} \mathrm{ohm}-\mathrm{cm}$.

(a) Three resistance $2\mathrm{\Omega },{\mathrm{R}}_2$, and $5\mathrm{\Omega }$ are connected in series, their effective resistance is $10\mathrm{\Omega }$. What is the value of ${\mathrm{R}}_2$?

(b) What will be the effective resistance if they are connected in parallel?

Three equal resistors connected in series across a source of emf together dissipate power $‘\mathrm{X}’$. What would be the power dissipated if the same resistors are connected in parallel across the same source of emf?