Q180 / 180 · COMEDK 2015 · Physics
Two resistances $A$ and $B$ have colour codes orange, blue, white and brown, red, green, respectively. Then, ratio of their resistances $A: B$ is
- A$3: 1$
- B$1: 3$
- C$1: 3 \times 10^{4}$
- Correct answerD$3 \times 10^{4}: 1$
Solution
Using colour code for carbon resistor, (For A)
$\begin{array}{ccc}\text { Orange } & \text { Blue } & \text { White } \\ \downarrow & \downarrow & \downarrow \\ 3 & 6 & 9\end{array}$
$\therefore \quad R_{A}=36 \times 10^{9} \Omega$
Similarly, $($ For $B)$
$\begin{array}{ccc}\text { Brown } & \text { Red } & \text { Green } \\ \downarrow & \downarrow & \downarrow \\ 1 & 2 & 5\end{array}$
$\therefore \quad R_{B}=12 \times 10^{5} \Omega$
$\therefore \quad \frac{R_{A}}{R_{B}}=\frac{36 \times 10^{9}}{12 \times 10^{5}}$
$=3 \times 10^{4}$
$\therefore R_{A}: R_{B}=3 \times 10^{4}: 1$
Hence, the correct answer is option: 'D'.