In the circuit shown in Figure 5 below, the central zero galvanometer G shows no deflection when…
In the circuit shown in Figure 5 below, the central zero galvanometer G shows no deflection when the key K is closed. Calculate the value of resistor $R_1$.
Answer
Answer
AIWritten by AI (gemini) - it can contain mistakes.
Resistors $R_2 = 12\,\Omega$ and $R_3 = 24\,\Omega$ are in parallel:
$\frac{1}{R_4} = \frac{1}{12} + \frac{1}{24} = \frac{3}{24} \implies R_4 = 8\,\Omega$.
For a balanced Wheatstone bridge (zero galvanometer deflection):
$\frac{R_1}{R_4} = \frac{l}{100-l} \implies \frac{R_1}{8} = \frac{60}{40} = \frac{3}{2} \implies R_1 = \frac{60 \times 8}{40} = 12\,\Omega$.
Final answer: 12 Ω
From ISC 2027 Specimen Physics Paper 1, question 10(ii).