Question

The Wheatstone bridge shown in Fig. here, gets balanced when the carbon resistor used as $R_1$ has the colour code ( Orange, Red, Brown). The resistors $R_2$ and $R_4$ are $80\Omega$ and $40 \Omega$ respectively. Assuming that the colour code for the carbon resistors gives their accurate values, the colour code for the carbon resistor, used as $R_3$, would be :

• A. Red, Green, Brown
• B. Brown, Blue, Brown
• C. Grey, Black, Brown
• D. Brown, Blue, Black

Answer 1

Answer: (B)

Brown, Blue, Brown

Answer 2

$R_{1} = 32 \times10 = 320$
for wheat stone bridge
$\Rightarrow \frac{R_{1}}{R_{3}} = \frac{R_{2}}{R_{4}}$
$\frac{320}{R_{3}} = \frac{80}{40}$