NCERT Solution for Class 10 Science Chapter 12
Electricity
NCERT Books for Session 2020-2021
CBSE Board and UP Board
Exercises Questions
Page No-221
Questions No-14
Compare the power used in the 2 ohm resistor in each of the following circuits:
(i) a 6 V battery in series with 1 ohm and 2 ohm resistors, and
(ii) a 4 V battery in parallel with 12 ohm and 2 ohm resistors.
Given that: Potential difference, V = 6 V
(i) 1 Ω and 2 Ω resistors are connected in series. So, equivalent resistance of the circuit, R = 1 + 2 = 3 Ω
According to Ohm’s law, V = IR
⟹𝐼=𝑉/𝑅=6/3=2 𝐴
In series combination, the current in the circuit remains constant. Therefore power is given by
𝑃=𝐼²𝑅=(2)²×2=8 𝑊
(ii) 1 Ω and 2 Ω resistors are connected in parallel. ⟹𝐼=𝑉/𝑅=6/3=2 𝐴
In parallel combination, the voltage in the circuit remains constant. Therefore, power is given by 𝑃=𝑉²/𝑅 =4²/2=8 𝑊
Hence, in both the cases power remains same as 8W.
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(i) The circuit diagram is shown in figure.
Total resistance, R = 1Ω + 2Ω = 3Ω
Potential difference, V = 6 V
Power used in 2Ω resistor = I2R = (2)2 x 2 = 8 W
(ii) The circuit diagram for this case is shown :
Power used in 2 resistor = v2R =422 = 8 W.
Hence, in both the cases power remains same as 8W.