# A 2 W carbon resistor is color coded with green, black, red and brown respectively.

Question:

A 2 W carbon resistor is color coded with green, black, red and brown respectively. The maximum current which can be passed through this resistor is:

1. (1) $20 \mathrm{~mA}$

2. (2) $100 \mathrm{~mA}$

3. (3) $0.4 \mathrm{~mA}$

4. (4) $63 \mathrm{~mA}$

Correct Option: 1

Solution:

(1) Colour code for carbon resistor

$\mathrm{Bl}, \mathrm{Br}, \mathrm{R}, \mathrm{O}, \mathrm{Y}, \mathrm{G}$, Blue, $\mathrm{V}, \mathrm{Gr}, \mathrm{W}$

$\begin{array}{llllllllll}0 & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9\end{array}$

Resistance, $\mathrm{R}=\mathrm{AB} \times \mathrm{C} \pm \mathrm{D}$

$\therefore$ Resistance, $\mathrm{R}=50 \times 10^{2} \Omega$

Now using formula, Power, $\mathrm{P}=\mathrm{i}^{2} \mathrm{R}$

$\therefore \mathrm{i}=\sqrt{\frac{\mathrm{P}}{\mathrm{R}}}=\sqrt{\frac{2}{50 \times 10^{2}}}=20 \mathrm{~mA}$