Question

Green, Blue, Brown, Gold are the colour bands on resistors. Find its resistance.
(A) $580\Omega$
(B) $560\Omega$
(C) $480\Omega$
(D) $58\Omega$

Answer 1

Companies use colour coding system to denote the value of resistance in a resistor. Each colour band has a different purpose.

Complete answer:
To know the value of resistance colour code is used. These codes are printed in the form of a set of rings or strips.
Let the four colour bands present on a resistor be, $A,B,C,D$. Their purposes are,
Bands $A$ and $B$: These indicate the first two significant figures of resistance in ohm.
Band $C$: Indicates the decimal multiplier, that is the number of zeroes that follow the two significant figures $A$ and $B$.
Band $D$: Indicates the tolerance in present about the indicated value or in other words it represents the percentage accuracy of the indicated value. The tolerance in the case of gold is $\pm 5\%$ and in silver is $\pm 10\%$. If band $D$ is missing, then it indicates a tolerance of $\pm 20\%$.
So to formulate it, resistance $R = AB \times C \pm D\%$
Since, Green indicates $5$
Blue indicates $6$
Brown indicates ${10^1}$
Gold indicates tolerance of $\pm 5\%$
So, the resistance $R = 56 \times {10^1} \pm 5\%$
$R = 560 \pm 5\% \Omega$

Hence, option B is the correct answer.

Note:
Colour code for carbon resistors:

Colour	Figure	Multiplier
Black	$0$	${10^0}$
Brown	$1$	${10^1}$
Red	$2$	${10^2}$
Orange	$3$	${10^3}$
Yellow	$4$	${10^4}$
Green	$5$	${10^5}$
Blue	$6$	${10^6}$
Violet	$7$	${10^7}$
Grey	$8$	${10^8}$
White	$9$	${10^9}$