Introduction

Electricity is a fundamental area of physics that plays a huge role in our lives, powering our houses, automobiles, and an infinite number of electrical and electronic equipment.Students are introduced to the exciting world of electrical circuits, Ohm’s law, resistors, resistor combinations, household power supply, practical uses of heating effect, and several other vital ideas in this chapter.

Understanding these topics is critical not just for passing your examinations, but also for laying solid physics foundations. We have produced extensive NCERT answers that cover all of the major subjects, provide step-by-step explanations, and offer practice problems to help you comprehend. Let us plunge into this thrilling chapter together and discover the unexplained nature of electrical phenomena.

Question-1

A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel.The equivalent resistance of this combination is R’,  then find the ratio of R/R’

Solution

Question-2

Which of the following does not represent electrical power in a circuit?

• a).     I²R
• b).     IR²
• c).     VI
• d).     V²/R

Solution

b). IR²

Question-3

An electric bulb is rated 220 V and  100 W. When it is operated on 110 V, the power consumed will be

• a). 100 W
• b). 75 W
• c). 50 W
• d). 25 W

Question-4

Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combination would be:

• a). 1:2
• b). 2:1
• c). 1:4
• d). 4:1

Solution

• c). 1:4

Question-5

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

Solution

To measure the potential difference in a circuit, a voltmeter should always be connected parallel to the circuit, but an ammeter ought to constantly be connected in series with the circuit.

Question -6

A copper wire has diameter 0.5 mm and resistivity of 1.6 × 10^–8 Ω m. What will be the length of this wire to make its resistance 10 Ω? How much does the resistance change if the diameter is doubled?

Solution

Question-7

The values of current I flowing in a given resistor for the corresponding values of potential difference V across a resistor are given below.Plot a graph between V and I   and calculate the resistance of the resistor.

I (Ampere)	0.5	1.0	2.0	3.0	4.0
V (Volts)	1.6	3.4	6.7	10.2	13.2

Solution

Model calculation

I (Ampere)	0.2	0.4	0.6	0.8	1.0
V (Volts)	0.6	1.2	1.8	2.4	3.0

QUESTION – 8

When a 12 V battery is connected across an unknown resistor,there is a current of 2.5 mA in the circuit.Find the value of the resistance of the resistor.

SOLUTION

QUESTION – 9

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?

Solution

Question -15 with solution

Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to electric main supply.What current is drawn from the line if the supply voltage is 220 V ?