NCERT Solutions for Class 10 Science Chapter 12

NCERT Solutions for Class 10 Science Chapter 12 Electricity answers of intext questions given on Page 200 or Page 202 or Page 209 or Page 213 or Page 216 or Page 218 or Page 220 or Exercises in English Medium. All the solutions are updated for new academic session 2020-21. UP Board students also download UP Board solutions for Class 10 Science chapter 12 in Hindi Medium. 10th Science Chapter 12 answers given on पेज 222 के उत्तर or पेज 224 के उत्तर or पेज 232 के उत्तर or पेज 237 के उत्तर or पेज 240 के उत्तर or पेज 242 के उत्तर or पेज 245 के उत्तर and अभ्यास के प्रश्न उत्तर in Hindi medium are also given free to download.

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NCERT Solutions for Class 10 Science Chapter 12

Class: 10	Science (English and Hindi Medium)
Chapter 12:	Electricity

10th Science Chapter 12 Answers in English & Hindi Medium

NCERT Solutions for Class 10 Science Chapter 12 Electricity all question answers, whether intext or exercises questions. All are updated as per student’s suggestions for 2020-21. Download NCERT Solutions as well as Offline Apps for other subjects also. Offline Apps are such that once downloaded, no need of internet later on.

Class 10 Science Chapter 12 Solutions Related Pages

What is meant by resistance of a conductor?

Resistance: The resistance of a conductor is its property by virtue of which it opposes the flow of current through it. It is equal to the ratio of the potential difference applied across the conductor to the current flowing through it.
Resistance = Potential difference / Current Or R = V/I.

What is an electric circuit? Distinguish between an open and a closed circuit.

A closed and continuous path along which an electric current flows is called an electric circuit.
In a torch, a switch provides a conducting link between a battery (a number of cells placed in proper order) and a bulb. When the switch is turned ON, an electric current flow through the bulb and its gives light. Such a continuous and closed path on an electric current is called an electric circuit. When the circuit is broken anywhere (or switch is turned OFF), the current stops flowing ant the bulb does not glow. An electric circuit through which no current flows is called an open circuit. An electric circuit through which current flows continuously is called a closed circuit.

What is meant by potential difference between two points? What is the SI unit of potential difference?

Potential difference: The potential difference between two points in an electric field is the amount of work done in bringing a unit positive charge from one point to the other.
V = W/Q or Potential difference = Work done / Charge
The SI unit of potential difference is joule/coulomb or volt.

Give four reasons why nichrome element is commonly used in household appliances.

In most of the household heating appliance, nichrome element is used because of the following reasons:
(i) Its melting point is high.
(ii) Its resistivity is large.
(iii) It can be easily drawn into thin wire.
(iv) It is not easily oxidised by the oxygen of the air when heated.

Questions for Practice

Question 1:
State Ohm’s law and write the condition in which this law is obeyed?
Answer 1:
This law states that the current (I) flowing through a conductor is directly proportional to the potential difference (V) applied across its ends, provided the temperature and other physical condition remain unchanged.
Mathematically, V ∝ I or V = RI
The proportionality constant R is called the resistance of the conductor.

Question 2:
What is an ammeter? How is it connected in a circuit?
Answer 2:
Ammeter: An ammeter (ampere + meter) is a device used to measure electric current in a circuit. An ammeter is always connected in series in a circuit, so that entire current, which we wish to measure, flows through it.

Questions from Board Papers

Question 1:
Distinguish between conventional current and electronic current. Or In an electric circuit state the relationship between the direction of conventional current and the direction of flow of electrons.
Answer 1:
conventional current and electronic current: When a conductor AB is connected across the terminals of a cell , free electrons begin to drift or move from its end B (connected to the negative terminal of the cell) to the end A (connected to the positive terminal of the cell). The current constituted by flowing electrons is called electronic current. Clearly, the direction of electronic current is from negative terminal to positive terminal.
By convention, the direction of motion of positive charges is taken as the direction of electric current. It is from positive terminal to negative terminal. As the electrons are negatively charged, the direction of conventional current is an electric circuit is taken as opposite to the direction of the flow of electrons.

Question 2:
Why does the cord of an electric heater not glow while the heating element does?
Answer 2:
Both the cord and the heating element of an electric heater carry the same current. But the heating element becomes hot due to its high resistance (H=I²Rt) and begins to glow. The cord remains cold due to its low resistance and dos not glow.

Important Questions on 10th Science Chapter 12

How is a voltmeter connected in the circuit to measure the potential difference between two points?

To measure the potential difference, a voltmeter should be connected in parallel.

A battery of 9 V is connected in series with resistors of 0.2 Ω, 0.3 Ω, 0.4 Ω, 0.5 Ω and 12 Ω, respectively. How much current would flow through the 12 Ω resistor?

Total resistance of resistors when connected in series is given by
R = R1 + R2 + R3 + R4 + R5 = ⟹ R= 0.2 Ω + 0.3 Ω + 0.4 Ω + 0.5 Ω + 12 Ω =13.4 Ω
According to Ohm’s law, V = IR

I = V/R = 9/13.4 = 0.67 A

There is no current division occurring in a series circuit. So, the current through the 12 Ω resistor will be same as 0.67 A.

Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?

Energy consumed by an electrical appliance is given by H = Pt
For the TV set:
Power W = 250 W and time t = 1 hour = 3600 seconds
So, energy consumed H = 250 × 3600 = 900000 J
For the toaster:
Power W = 1200 W and time t = 10 minutes = 600 seconds
So, energy consumed H = 1200 × 600 = 720000 J
Hence, TV set uses more energy than toaster.

Why is the tungsten used almost exclusively for filament of electric lamps?

The melting point and resistivity of tungsten are very high. It does not burn readily at a high temperature. The electric lamps glow at very high temperatures. Hence, tungsten is mainly used as heating element of electric bulbs.

Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?

The conductors of electric heating devices such as bread toasters and electric irons are made of alloy because resistivity of an alloy is more than that of metals. It produces large amount of heat and do not burn easily.

Why is the series arrangement not used for domestic circuits?

There is voltage division in series circuits. Each component of a series circuit receives a small voltage for a large supply voltage. As a result, the amount of current decreases and the device becomes hot. Hence, series arrangement is not used in domestic circuits.

Why are copper and aluminium wires usually employed for electricity transmission?

Copper and aluminium wires have low resistivity. They are good conductors of electricity. Hence, they are usually employed for electricity transmission.

What does an electric circuit mean?

An electric circuit is the pathway in which current can flow. It consists of electric devices, switching devices, source of electricity, etc. that are connected by conducting wires.

Name a device that helps to maintain a potential difference across a conductor.

A cell, battery, power supply, etc. helps to maintain a potential difference across a conductor.

What is meant by saying that the potential difference between two points is 1 V?

When 1 J of work is required to move a charge of 1 C from one point to another, then it is said that the potential difference between the two points is 1 V.

V = W/Q

1 V = 1 j / 1 C

On what factors does the resistance of a conductor depend?

The resistance of a conductor depends upon the following factors:
Length of the conductor
Cross-sectional area of the conductor
Material of the conductor
Temperature of the conductor.

Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?

The resistivity of an alloy is higher than the pure metal and it does not corrode easily. Moreover, even at high temperatures, the alloys do not melt readily. Hence, the coils of heating appliances such as electric toasters and electric irons are made of an alloy rather than a pure metal.

What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series?

In parallel there is no division of voltage among the appliances. The potential difference across each appliance is equal to the supplied voltage and the total effective resistance of the circuit can be reduced by connecting electrical appliances in parallel.

Why does the cord of an electric heater not glow while the heating element does?

he heating element of an electric heater is a resistor. According to Joule’s law of heating, the amount of heat produced by it is proportional to its resistance.
H = I^2 Rt
The resistance of the element of an electric heater is very high. As current flows through the heating element, it becomes too hot and glows red. On the other hand, the resistance of the cord is low. It does not become red when current flows through it.

What determines the rate at which energy is delivered by a current?

he rate of consumption of electric energy in an electric appliance is called electric power. Hence, the rate at which energy is delivered by a current is the power of the appliance.