Solved Sample Paper 4 — Question 24

(a) In the circuit, there are two parts. In the first part, resistors of R₁ (6 Ω) and R₂ (2 Ω) are connected in parallel. If the equivalent resistance of this part is R_p then

$\dfrac{1}{{R}_P} = \dfrac{1}{6} + \dfrac{1}{2} \\[0.5em] \dfrac{1}{{R}_P} = \dfrac{1 + 3}{6} \\[0.5em] \dfrac{1}{{R}_P} = \dfrac{4}{6} \\[0.5em] \dfrac{1}{{R}_P} = \dfrac{2}{3} \\[0.5em] \Rightarrow {R}_P = \dfrac{3}{2} = 1.5 Ω$

Hence, R_P = 1.5 Ω

In the second part, R_P (1.5 Ω) and R₃ (6 Ω) are connected in series. If the equivalent resistance of this part is R_s then

R_s = (1.5 + 6) Ω = 7.5 Ω

Hence, combined resistance = 7.5 Ω

(b) The earth wire is connected to the metallic body of the appliance.