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

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 :-

**Exe-1 Class-10**

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

**Page-150**

**Question 1.**

**(a)** What do you understand by the term electric work ?

**Answer:**

**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.

**Answer:**

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 ?

**Answer:**

**Two bigger units of electric work :**

- Kilo – Joule (kJ) = 10
^{3}J - Mega-joule (Mj) = 10
^{6}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.

**Answer:
**

**Question 3.**

State three factors which determine the quantity of heat produced in a conductor.

**Answer:**

Three factors which determine heat produced in a conductor :

Heat produced = Energy Work done

W=H=I^{2}Rt

∴ 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.

**Answer:
**

**Question 5.**

**Derive an expression for electric power connecting :**

**(a)** Current and resistance.

**(b)** Current and potential difference.

**(c)** Potential difference and resistance.

**Answer:
**

**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.

**Answer:**

**(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 :**

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

**Answer:
**

**Question 8.**

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

**Answer:
**

**Question 9.**

Distinguish between kilo-watt and kilowatt hour.

**Answer:
**

**Question 10.**

How many kilowatt is equal to one hour power ?

**Answer:
**

** ****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 :
**

**Answer:**

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

**Answer:**

**3. The unit for electric work in SI system :**

(a) Joule

(b) watt

(c) watt second

(d) watt hour

**Answer:**

(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

**Answer:**

(c) 40 Ω

**5. Kilowatt hour is commercial unit of :**

(a) power

(b) electric energy

(c) heat energy

(d) mechanical energy

**Answer:**

(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

**Answer:**

(d) commercial units of electric energy and power

**Numerical Problem ****on Electric Energy**

**on Electric Energy**

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

Page-152

**Practice Problems 1**

**Question 1.**

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

**Answer:
**

**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.

**Answer:
**

**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.

**Answer:
**

**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.

**Answer:
**

**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.

**Answer:
**

**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.

**Answer:
**

**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.

**Answer:
**

**Question 2.**

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

**Answer:
**

**Question 3.**

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

**Answer:
**

**Practice Problems 5**

**Question 1.**

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

- its power
- p.d. at its ends

**Answer:
**

**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.

**Answer:
**

**Read Next 👇 Click on Page Number Given Below 👇**