NCERT Exemplar Class 10 Science Chapter 12 Electricity

Chapter 12 Electricity NCERT Exemplar for class 10 Science

NCERT Exemplar Solutions for Class 10 Science Chapter 12 Electricity are the study materials necessary for you to understand the questions that can be chosen to be asked from the Class 10 Science Electricity chapter. It is crucial for students to get acquainted with this chapter in order to score excellent marks in their board examination. This solution provides answers to the questions provided in NCERT Class 10 Exemplar book.

To help students grasp all the concepts clearly and in-depth,simply acad is providing free access to NCERT Exemplar for chapter 12 in pdf format for free. Fasten your belts and practice each and every question with full heart out for good scores. These exemplars will enable students to learn the correct answers to all the questions given at the end of the chapter. These NCERT Exemplars are prepared by experts and can be used by students as an effective learning tool to improve their conceptual understanding.

Take a closer look at Class 10 Science Chapter 12 NCERT Exemplar below.

1. A cell, a resistor, a key and ammeter are arranged as shown in the circuit diagrams of Figure12.1. The current recorded in the ammeter will be

(a) maximum in (i)

(b) maximum in (ii)

(c) maximum in (iii)

(d) the same in all the cases

Soln:

The answer is (d) the same in all the cases

Explanation:

There are no changes in any of the circuits, hence current will be same in all the circuits.

2. In the following circuits (Figure 12.2), the heat produced in the resistor or combination of resistors connected to a 12 V battery will be

(a) same in all the cases

(b) minimum in case (i)

(c) maximum in case(ii)

(d) maximum in case(iii)

Soln:

The answer is (c) maximum in case(ii)

Explanation

Here two transistors are in series. In figure (iii) total resistance will be less than individual resistances as they are connected parallel. Higher resistance produces more heat hence option c) is the right answer.

3. Electrical resistivity of a given metallic wire depends upon

(a) its length

(b) its thickness

(c) its shape

(d) nature of the material

Soln:

The answer is (d) nature of the material

4. A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross-section of the filament in 16 seconds would be roughly

(a) 1020

(b) 1016

(c) 1018

(d) 1023

Soln:

Answer is (a) 1020

Explanation:

I = Q/t

Q= It

Q= 1 x 16

Q= 16 q

Q=ne

n = Q/e

n = 16 /1.6 x 10-19

n = 10 x 1019

n = 1020 electrons

The number of electrons flowing is 1020 electrons

5. Identify the circuit (Figure 12.3) in which the electrical components have been properly connected.

(a) (i)

(b) (ii)

(c) (iii)

(d) (iv)

Soln:

The answer is (b) (ii)

6. What is the maximum resistance which can be made using five resistors each of 1/5 Ω?

(a) 1/5 Ω

(b) 10 Ω

(c) 5 Ω

(d) 1 Ω

Soln:

The answer is (d) 1 Ω

Explanation:

Maximum resistance is obtained when resistors are connected in series.

R=

15+15+15+15+15

= 5/5

= 1Ω

7. What is the minimum resistance which can be made using five resistors each of 1/5 Ω?

(a) 1/5 Ω

(b) 1/25 Ω

(c) 1/10 Ω

(d) 25 Ω

Soln:

Answer is (b) 1/25 Ω

Explanation:

Minimum resistance is obtained when resistors are connected parallel

1/R = 5 + 5 + 5 +5 +5= 25 Ω

R=1/25Ω

8. The proper representation of the series combination of cells (Figure 12.4) obtaining maximum potential is

(a) (i)

(b) (ii)

(c) (iii)

(d) (iv)

Soln:

The answer is (a) (i)

Explanation:

Here positive terminal of the next cell is adjacent to the negative terminal of the previous cell.

9. A cylindrical conductor of length l and uniform area of crosssection A has resistance R. Another conductor of length 2l and resistance R of the same material has an area of cross-section

(a) A/2

(b) 3A/2

(c) 2A

(d) 3A

Soln:

Answer is (c) 2A

Explanation:

P=

RAl

When Length doubles

P=

RAl

RAl

= P=

RA2l

A=2A

10. A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with resistances R1, R2 and R3 respectively (Figure.12.5). Which of the following is true?

(a) R1 = R2 = R3

(b) R1 > R2 > R3

(c) R3 > R2 > R1

(d) R2 > R3 > R1

Soln:

The answer is (c) R3 > R2 > R1

Explanation:

Current flow is inversely proportional to resistance. Highest resistance will show less flow of current hence answer is c).

11. If the current I through a resistor is increased by 100% (assume that temperature remains unchanged), the increase in power dissipated will be

(a) 100 %

(b) 200 %

(c) 300 %

(d) 400 %

Soln:

Answer is (c) 300 %

Explanation:

Heat generated by a resistor is directly proportional to the square of the current. Hence, when the current becomes double, dissipation of heat will multiply by 2 =4. This means there will be an increase of 300%.

12. The resistivity does not change if

(a) the material is changed

(b) the temperature is changed

(c) the shape of the resistor is changed

(d) both material and temperature are changed

Soln:

Answer is (c) the shape of the resistor is changed

13. In an electrical circuit, three incandescent bulbs A, B and C of rating 40 W, 60 W and 100 W respectively are connected in parallel to an electric source. Which of the following is likely to happen regarding their brightness?

(a) The brightness of all the bulbs will be the same

(b) The brightness of bulb A will be the maximum

(c) The brightness of bulb B will be more than that of A

(d) The brightness of bulb C will be less than that of B

Soln:

Answer is (c) Brightness of bulb B will be more than that of A

Explanation:

Bulbs are connected in parallel so the resistance of combination would be less than the arithmetic sum of the resistance of all the bulbs. So. there will be no negative effect on the flow of current. As a result, bulbs would glow according to their wattage.

14. In an electrical circuit, two resistors of 2 Ω and 4 Ω respectively are connected in series to a 6 V battery. The heat dissipated by the 4 Ω resistor in 5 s will be

(a) 5 J

(b) 10 J

(c) 20 J

(d) 30 J

Soln:

Answer is (c) 20 J

Explanation:

Equivalent resistance of the circuit is R = 4+2 = 6Ω

current, I= V/R = 6/6= 1A

the heat dissipated by 4-ohm resistor is, H = I2Rt = 20J

15. An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?

(a) 1 A

(b) 2 A

(c) 4 A

(d) 5 A

Soln:

The answer is (d) 5 A

Explanation:

P=V x I

Or 1000 w = 220v x I

I =

1000w220v

= 4.54 A

= 5 A