Question

Compare the power used in the 2Ωresistor in each of the following circuits: (i) a 6 V battery in series with 1Ωand 2Ωresistors, and (ii) a 4 V battery in parallel with 12Ωand 2Ωresistors.

Answer 1

ⅰ. In case of series circuit,
total resistance, R = R₁ + R₂
R = 3Ω
As in series circuit current is constant so,I = V/R
= 6/3
= 2A
Now, voltage drop across 2Ω resistor = V₂ = I ×​ R₂
= 2 × 2 = 4 Volt
Power across 2Ω resistor P₂ = I ×​ V₂
= 2×4 = 8 watt
ⅱ. )
In case of parallel combination, Voltage drop is same across both the resistors but current is different so,
Current across 2Ω resistor I₂ = V/R₂
= 4/2 = 2A
so power across 2Ω resistor is = P₂ = V ×​ I₂
= 4 × 2 = 8 watt
Hence,we found that power is same in both the cases.