Class-10 Goyal Brothers Electric Energy, Power and Household Circuits ICSE Physics Solutions Ch-9 . We Provide Step by Step Answer of Exercise, MCQs, Numerical Problem Questions of Exercise-1 & 2 Goyal Brothers Electric Energy, Power and Household Circuits ICSE Class-10 . Visit official Website CISCE  for detail information about ICSE Board Class-10 Physics.

## Electric Energy, Power and Household Circuits Class-10 Goyal Brothers ICSE Physics Solutions Ch-9

-: Select Topics :-

Exercise-1

MCQ -1

Numerical Problem-1

Exercise-2

MCQ -2

### Exe-1 Class-10

Electric Energy, Power and Household Circuits Goyal Brothers ICSE Physics Solutions Ch-9

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Question 1.
(a) What do you understand by the term electric work ?
Electric work : “Electric work is said to be done when an electric charge flows through a conductor, at some potential difference.”

(b) State and define SI unit of electric work.
S.I. unit of electric work → Joule (J)
1J = 1 volt × 1 coulomb
1 Joule : “Is the amount of work done when a charge of one coulomb flows through a conductor at a pot. diff. of 1 volt.”

(c) Name two bigger units of electric work. How are they related to SI unit ?
Two bigger units of electric work :

1. Kilo – Joule (kJ) = 103 J
2. Mega-joule (Mj) = 106 J

Question 2.
Derive an expression for electric work connecting :

(a) Current, resistance and time
(b) Current, potential difference and time.
(c) Potential difference, resistance and time.

Question 3.
State three factors which determine the quantity of heat produced in a conductor.
Three factors which determine heat produced in a conductor :
Heat produced = Energy Work done
W=H=I2Rt
∴ Three factors are I — current
R — Resistance of conductor
t — time for which current flows.

Question 4.

(a) What do you understand by the term electric power ?
(b) State SI unit of electric power and define it
(c) Name two bigger units of electric power and their relation with SI unit.

Question 5.
Derive an expression for electric power connecting :

(a) Current and resistance.
(b) Current and potential difference.
(c) Potential difference and resistance.

Question 6.

(a) What do you understand by term electric energy ?
(b) Name and define the smallest commercial unit of electric energy.
(c) Name and define the standard commercial unit of electric energy.

(a) Electric energy : E = P × t = VIt
“Electric energy is the product of power and time.” i.e. electric energy consumed by an electrical appliance is produced of ‘power rating’ and ‘time’ for which it is used.
(b) Unit of electric energy → Joule (J)
S.I. unit of electric work → Joule (J)
1J = 1 volt × 1 coulomb
1 Joule : “Is the amount of work done when a charge of one coulomb flows through a conductor at a pot. diff. of 1 volt.”
(c) Standard Commercial unit of Electric Energy : Kilo-watt-Hour 1 kwH : “Is the amount of electrical energy consumed when an electrical appliance having a power rating of 1 kilowatt is used for 1 hour.”

Question 7.
With respect to electricity, define :

1. watt hour
2. watt
3. kilowatt
4. kilowatt hour. Amongst the above units, which are the units of : (i) electric energy (ii) electric power.

Question 8.
How many joules of energy is equal to one kilowatt hour?

Question 9.
Distinguish between kilo-watt and kilowatt hour.

Question 10.
How many kilowatt is equal to one hour power ?

Multiple Choice Questions-1

### Electric Energy, Power and Household Circuits Class-10 Goyal Brothers  ICSE Physics Solutions

1. A bulb has a resistance of 20 Ω and the p.d across its terminals is V. If the bulb is usedfor t seconds then energy consumed by the bulb is :

2. A current Iflows through a resistance R for the time ‘t’, the electric energy consumed by the resistance is :

3. The unit for electric work in SI system :
(a) Joule
(b) watt
(c) watt second
(d) watt hour
(a) Joule

4. An electric appliance has a rating of 1000 W – 200 V. The resistance of the element of electric appliance is :
(a) 200 Ω
(b) 400 Ω
(c) 40 Ω
(d) 4000 Ω
(c) 40 Ω

5. Kilowatt hour is commercial unit of :
(a) power
(b) electric energy
(c) heat energy
(d) mechanical energy
(b) electric energy

6. Kilowatt hour and kilowatt are :
(a) SI units of power and electric energy
(b) commercial units of power and electric energy
(c) SI units of-electric energy and power
(d) commercial units of electric energy and power
(d) commercial units of electric energy and power

### Numerical Problem on Electric Energy

Electric Energy, Power and Household Circuits Class-10 Goyal Brothers  ICSE Physics Solutions

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Practice Problems 1

Question 1.
Calculate the energy released by a heater, which draws a current of 5A at 220 V for 1 min.

Question 2.
An electric device consumes 8640 J of energy in 30 min. while operating at 24 V. Calculate the current drawn by the device.

Practice Problems 2

Question 1.
An ekctric kettle draws a current of4A for 2.5 min. if the resistance of its element is 100 Ω , calculate the electric energy drawn by kettle in kilojoules.

Question 2.
A soldering iron draws an energy of 43200 J in 4 min, when the current flowing through its element is 6 A, calculate the resistance of its heating element.

Practice Problems 3

Question 1.
Calculate the heat energy given out by the filament of an electric bulb in 20 s, when its resistance is 4 Ω and p.d. across its ends in 12 V.

Question 2.
An electric device gives out 5760 J of heat energy in 1 min, when current flows through it at a p.d. of 24 V. Find the resistance of the device.

Practice Problems 4

Question 1.
An electric heater draws a current of 3.5 A at a p.d. of 250 V. Calculate the power of 4 such heaters.

Question 2.
An electric bulb is rated 500 W – 200 V. Calculate the magnitude of current.

Question 3.
An electric heater of power 1000 W, draws a current of 5.0 A. Calculate the line voltage.

Practice Problems 5

Question 1.
An electric heater has a resistance of 40 Ω and draws a current of 4 A. Calculate :

1. its power
2. p.d. at its ends

Question 2.
An electric heater of power 900 W, has a resistance of 36 Ω Calculate the magnitude of current and the p.d. at its ends.
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