NCERT Class 10 Science Chapter 12 Electricity Extra Questions and Answers
Class 10 Science Chapter 12 Extra Inside Questions and Answers – Electricity. Here in this Page Class X Students can Learn Extra Questions & Answer 12th Chapter Science fully Inside.
We Provided Here Electricity Science Chapter 12 Long Answer Type Question, Multiple Choice Questions & Answer, Short Answer Type Questions (2 or 3 marks), and Very Short answer Type Question (1 marks) Solution.
Class 10 Science Chapter 12 Extra Question with Answer – Electricity
Science Chapter 12 Electricity Class 10 Inside 5 Marks, 3 marks, 2 Marks & And 1 Marks Important Questions and Answers.
1.) Fill in the blanks.
1.) In an electric circuit, the direction of electric current is taken as ______ to the direction of the flow of electrons.
Ans:
In an electric circuit, the direction of electric current is taken as opposite to the direction of the flow of electrons.
2.) An instrument ____ is used to measure current in the electrical circuit.
Ans:
An instrument ammeter is used to measure current in the electrical circuit.
3.) An instrument_____ is used to measure potential difference between two points in an electrical circuit.
Ans:
An instrument voltmeter is used to measure the potential difference between two points in an electrical circuit.
4.) The resistance of the conducting wire is _______ proportional to the area of cross section of the conducting wire.
Ans:
The resistance of the conducting wire is inversely proportional to the area of cross section of the conducting wire.
5.) The resistivity of the alloys is ______ than the resistivity of the metals.
Ans:
The resistivity of the alloys is greater than the resistivity of the metals.
6.) In series combination of resistors, the effective resistance is _____ than each individual resistance of the resistor connected in series.
Ans:
In series combination of resistors, the effective resistance is greater than each individual resistance of the resistor connected in series.
7.) In parallel combination of resistors, the effective resistance is ______ than each individual resistance of the resistor connected in parallel.
Ans:
In parallel combination of resistors, the effective resistance is less than each individual resistance of the resistor connected in parallel.
8.) According to Joule’s law of heating, the heat produced in a resistor is directly proportional to the square of ______.
Ans:
According to Joule’s law of heating, the heat produced in a resistor is directly proportional to the square of current for a given resistance.
9.) The bulb filaments are made from the strong metal_____.
Ans:
The bulb filaments are made from the strong metal’s tungsten.
10.) In domestic wiring, ______ combination is used.
Ans:
In domestic wiring, parallel combination is used.
2.) Multiple Choice questions:
1.) The SI unit of electrical power is
a) kilowatt
b) watt
c) joule
d) joule/s
Ans: b) watt
2.) 1KWh =
a) 3.6*106 joule
b) 3.6*10-6 joule
c) 36*106 joule
d) 36*10-6 joule
Ans: a) 3.6*106 joule
Since, 1KWh = 3.6*106 joule
3.) The bulbs are usually filled with ______ gases to prolong the life of filament.
a) active nitrogen and argon
b) inactive nitrogen and argon
c) inactive oxygen and argon
d) inactive nitrogen and oxygen
Ans: b) inactive nitrogen and argon
4.) The resistance of the conductor depends on
a) length of the conductor
b) area of cross section of the conductor
c) nature of the material of the conductor
d) all of the above
Ans: d) All of the above
4.) The SI unit of resistivity is
a) mho m-1
b) ohm
c) ohm m
d) mho
Ans: c) ohm m
6.) The material having lowest resistivity i.e. highest conductivity is the
a) copper
b) iron
c) aluminium
d) silver
Ans: d) silver
7.) In series combination, which of the following remains constant
a) voltage
b) resistance
c) resistivity
d) current
Ans: d) current
8.) In parallel combination which of the following remains constant
a) current
b) voltage
c) resistance
d) resistivity
Ans: b) voltage
9.) According to Joule’s law of heating, the heat produced in a resistor is directly proportional to
a) square of current for a given resistance
b) resistance for a given current
c) time for which current flows through the resistor
d) all of the above
Ans: d) all of the above
10.) The commercial unit of electrical energy is
a) joule
b) kW
c) kWh
d) W
Ans: c) kWh
3.) Very short answer questions:
1.) What is an electric current? Give it’s SI unit.
Ans:
- Electric current is the amount of charge flowing through a particular area in unit time.
- The SI unit of electric current is ampere or A.
2.) What is an ammeter and how it is connected in an electrical circuit?
Ans:
- An ammeter is an electrical instrument which is used to measure an electric current flowing through a circuit.
- It is always connected in series with in a circuit through which the current is to be measured.
3.) What is voltmeter and how it is connected in an electrical circuit?
Ans:
The potential difference is measured using voltmeter. And voltmeter is always connected in parallel across the points between which the potential difference is to be measured.
4.) State Ohm’s law?
Ans:
According to Ohm’s law, the potential difference V across the ends of the given metallic wire in an electric circuit is directly proportional to the current flowing through it.
5.) What is variable resistance?
Ans:
- A component which is used to regulate current without changing the voltage source is called as the variable resistance.
6.) What are conductors?
Ans:
Conductors are the materials which are having low resistivity and hence they are capable of conducting electricity.
7.) What are conductors?
Ans:
- Conductors are the materials which are having low resistivity and hence they are capable of conducting electricity.
8.) What are insulators?
Ans:
- Insulators are those materials which are having high resistivity and hence they are not capable of conducting electricity.
9.) Which effect is utilised in electric heaters and electric irons?
Ans:
- The heating effect of electric current i.e. Joule’s heating effect is utilised in electric heaters and electric irons.
10.) What is the mathematical statement of Joule’s law of heating?
Ans:
- According to Joule’s law of heating, the heat produced in a resistor is given by,
H= I2Rt
11.) What is an electric power?
Ans:
The energy consumed or dissipated in an electric circuit is called as the electric power.
4.) Short answer questions:
1.) What happens to the resistivity of the material if the shape of the material is changed?
Ans:
- We know that, resistivity of the material depends on the resistance R, area of cross section, length of the material and also on the nature of the material and temperature.
- But, if the shape of the material is changed then resistivity of the material does not change.
2.) Draw a circuit diagram showing series combination of resistors.
Ans:
The following circuit diagram shows the series combination of resistors R1, R2 and R2.
Fig. Series Combination of resistors
3.) Draw a circuit diagram showing parallel combination of resistors.
Ans:
The following diagram shows the parallel combination of resistors R1, R2 and R3.
Fig. Parallel Combination of resistors
4.) Why the resistance of the ammeter is low explain?
Ans:
- We know that, the ammeter is connected in series with the circuit or resistor to measure the current flowing through it.
- And we know that, in series combination of resistors the current flowing is constant. Which is given by,
I= V/R
- But the applied voltage is constant and if resistance is less I is more. Hence for maximum current the circuits are mainly designed such that they are having low resistance.
- For ideal ammeter, the resistance should be zero due to which infinite current flows through it.
In case you are missed :- Previous Chapter Extra Questions
5.) What is the role of fuse in domestic purposes?
Ans:
- When maximum current flows then initially fuse get heated and then melts in that way breaks that branch so that electrical appliances are protected from large current and damaging. The fuses are having specific melting point, if temperature is increased due to extra current and heating and if temperature becomes more than melting point of fuses, they get melts and protects the circuit.
- And thus, whole circuit works as it is with no any time lag. Because of this fuse are mostly used to protect electrical appliances.
6.) If the VI graph is showing straight line graph passing through origin then what it explains?
Ans:
- If the graph plotted between V and I is a straight line passing through origin which indicates that potential difference V is directly proportional to current I flowing through the circuit. And it verifies the Ohm’s law.
- And the slope of that VI graph gives the value of resistance which remains constant.
7.) If the current flowing is 0.3A and an voltage of 220 V is given to an electric bulb then find the power of the bulb?
Ans:
Given that,
Current I = 0.3A
Voltage V= 220V
The power is given by,
P = VI = 220*0.3= 66 J/s
Thus, power of the bulb is 66J/s or 66 W.
8.) What is the potential difference of the resistor if the heater is generating 200J of heat per second due to 7 ohm resistance?
Ans:
Given that,
H= 200J
Resistance R = 7 ohm
V=?
We know that, according to Joule’s law of heating,
H= I2Rt
I2 = H/Rt = 200/7*1 = 28.57
And I = 5.34 A
Now, potential difference across the resistor is given by,
V= IR = 5.34*7= 37.41 V
9.) Draw the symbols of the following components.
a) an electric cell
b) electric bulb
c) a resistor of resistance R
d) variable resistance
e) ammeter
f) voltmeter
Ans:
5.) Long answer questions:
1.) What is equivalent resistance of the resistors 6 ohm, 12 ohm, 24 ohm and 3 ohm if connected in series and parallel combination.
Ans:
- We know that, in series combination of resistors the effective resistance or equivalent resistance is the sum of all resistors connected in series combination.
- Thus, if resistors of resistances 6ohm, 12ohm, 24ohm and 3 ohm are connected in series then the equivalent resistance is given by,
Re= 6 + 12 + 24 + 3 = 45 ohm
- Thus, equivalent resistance when resistors connected in series combination is 45 ohm.
- Now, when all the resistors of resistances 6ohm, 12ohm, 24ohm and 3 ohm are connected in parallel combination then the equivalent resistance is given by,
1/Re = 1/6 + 1/12 + 1/24 + 1/3
1/ Re = 4 + 2 + 1 + 8 = 15
Thus, 1/Re = 15
- And hence, Re = 1/15 = 0.066 ohm.
2.) In series combination the current flowing through the circuit is constant. Give reason with example.
Ans:
- In series combination of resistors, the effective resistance is the sum of resistances connected in series combination. And hence the effective resistance is greater than individual resistance. And hence the total current through the circuit decreases. The total current is equal to the current through each resistor.
- To infer that the current flowing through the resistors connected in series we can do the following experiment:
Fig.1
- Consider the three resistors R1, R2 and R3 are connected in series and battery of voltage V is connected to them in series. Now we can connect an ammeter A as shown in fig.1 to measure the total current through the circuit. And let the current noted is I.
- Now we connect the same ammeter A1 near to resistor R1 as shown in fig.2 to measure the current through the resistor and we will note the same current I.
Fig.2
- To measure the current through resistor R2 we will connect the ammeter A2 as shown in fig.3 and we get the same current I.
Fig.3
- Finally, when we connect the ammeter A3 as shown in fig.4 to measure the current through the resistor R3 we get the same current as I.
Fig.4
- Thus, from above all procedure, it is concluded that in series combination of resistors the current through each resistor is equal to the total current through the whole circuit.
- Thus, in series combination of resistors the current will be same through all the resistors and the circuit.
3.) When resistors are connected in parallel the potential difference across each resistor is different. Give reason with example.
Ans:
- In parallel combination of resistors, the voltage across each resistor will be same as the voltage applied to the circuit. The effective resistance of parallel combination of resistors is very low due to which high current flows through the circuit.
- But the current through each resistor is different and their total sum is equal to the total current through the circuit. Because of this advantage the parallel combination is used in domestic wiring to protect the circuit from high currents and to adjust the appliances simultaneously.
- Now to infer that the potential difference across each resistor connected in parallel is same let us consider an electric circuit in which three resistors R1, R2 and R3 are connected in parallel and battery of voltage V is applied across them in a series.
- Now first we measure the voltage at points A and B by voltmeter V and we have noted the voltage as V as shown in fig.1
Fig.1
- Now, to measure the potential difference across the resistor R1 we connect the voltmeter V1 parallel to it as shown in fig2 and noted the voltage as V.
Fig.2
- Similarly, to measure the potential difference across the resistor R2 we will connect a voltmeter V2 parallel to it as shown in fig.3 and noted the same voltage V.
Fig.3
- Finally, we will connect the voltmeter V3 parallel to resistor R3 and measure the voltage across it we will get it as V as shown in fig.4
Fig.4
Thus, from above experiment we conclude that the potential difference across each resistor in parallel combination is same.
4.) Explain Joule’s heating effect.
Ans:
Joule’s law of heating gives the heating effect of an electric current. According to Joule’s law of heating, the heat produced in a resistor R is directly proportional to
- Square of the current through the resistor
- Resistance for a given current
- Time for which the current flows through the resistor
Mathematically, H = I2Rt
- To study the experimental demonstration of Joule’s heating effect, consider an electric circuit in which a cell, plug key and ammeter are connected in series with resistor R. the voltmeter to measure the voltage is connected parallel to the resistor as shown in fig.
- When potential difference V is applied to resistor R then current, I flows through it and current is the rate of flow of charge.
- Let for time t the current I flow through the resistor i.e. t be the time required to flow the charge Q through the circuit.
- In moving the charge Q through the potential difference V the circuit, the work is to be done and is given by W= VQ.
- This work is to be stored in the form of energy and hence energy supplied will be VQ.
- Then the power of the circuit is P = (VQ)/t = VI
- And hence the energy supplied in time t is P*t.
Fig. to study Joule’s heating effect
- This is the heat energy produced due to an electric current and is given by
H = P*t = VIt.
- Now, what about this energy produced? This energy produced in a circuit will be dissipated as heat energy in the resistor.
- Thus, the current flowing through the resistor R for a time t produces a heat energy
H = VIt = I2Rt.
- This heat energy produced depends on current, resistance and time for which the current is flowing. This proves the Joule’s law experimentally.
- In fuse wire circuits also heating effect occurs. The fuse wires are made from metal or an alloy of particular melting point like aluminium, copper, iron, lead etc. if large current flows through the circuit, the temperature of the fuse wire increases and due to which fuse wire get melted and circuit breaks. To protect the circuit from large current or heat produced due to large current fuses are used.
- The electric iron we use in daily life is also working on the Joule’s law of heating. In which electrical energy is converted into heat energy that can be used to press the cloths.
- Also, in electric heaters the Joule’s heating effect is observed, in which large current produces heat energy. This heat energy produced is used to heat the water.
In case you are missed :- Next Chapter Extra Questions