Question

A resistance of $600\,\,\Omega $ has the colour code given by 3 steps. The colour of strips (from left to right) is given by
(A) blue, black and brown
(B) blue, brown and black
(C) brown, blue and black
(D) brown, black and blue

Answer 1

Hint : Resistors are generally very small and it is hard to imprint resistance values on them. So, colour bands are imprinted on them to represent the electrical resistance. These colour bands are known as resistor colour code. 

Complete step by step solution:
A carbon-fabricated resistor can have up to ${4^{th}}$to ${6^{th}}$ bands. A ${5^{th}}$ band resistor is a lot accurate when referred to a ${4^{th}}$ band type, due to the reason of the addition of a third remarkable digit. A ${6^{th}}$ band resistor is similar to a ${5^{th}}$ band resistor, but it incorporates a temperature coefficient band.
Each colour in the resistor constitute a number if it's location from the ${1^{st}}$ to ${2^{nd}}$ band for a ${4^{th}}$ band type or ${1^{st}}$ to ${3^{rd}}$ band for a ${5^{th}}$ band and ${6^{th}}$ band type. 

Colour	Value
Black	$0$
Brown	$1$
Red	$2$
Orange	$3$
Yellow	$4$
Green	$5$
Blue	$6$
Violet	$7$
Grey	$8$
White	$9$

Memory aid were formed to easily remember the order of the colours. The most popular memory aid is that the “Big Boys Race Our Young Girls but Violet Generally Wins" in which the first letter of each word correlate to the first letter of the colour. If the colour is found on the ${3^{rd}}$ band for a ${4^{th}}$ band type or the ${4^{th}}$ band for a ${5^{th}}$ band and ${6^{th}}$ band type, then it is a multiplier.

Colour	Value
Black	$ \times 1$
Brown	$ \times 10$
Red	$ \times 100$
Orange	$ \times 1000$
Yellow	$ \times 10000$
Green	$ \times 100000$
Blue	$ \times 1000000$
Violet	$ \times 10000000$
Grey	$ \times 100000000$
White	$ \times 100000000$

We know that the number of zeroes is the same to the colour’s number as per the previous table.
The fourth band indicates the tolerance values. Here, two colours are added (gold and silver).

Colour	Value
Black	-
Brown	$ \pm 1\% $
Red	$ \pm 2\% $
Orange	$ \pm 3\% $
Yellow	$ \pm 4\% $
Green	$ \pm 5\% $
Blue	$ \pm 0.25\% $
Violet	$ \pm 0.1\% $
Grey	$ \pm 0.5\% $
White	-
Gold	$ \pm 5\% $
Silver	$ \pm 4\% $

 By using the above three tables we can calculate the colours representing $600\,\,\Omega $, from the first table we can take blue as six, and black as zero. From the second table we can take brown and use it to multiply.

Therefore, a resistance of 600Ω has the colour code of blue, black and brown.
Hence, the option (A) blue, black and brown is the correct answer.

Note: Five band resistors with a fourth band of silver or gold form an exception, and are utilized on specific or older resistors. The first two bands represent the significant digits, the third band is a multiplication factor, the fourth band is for tolerance and the fifth band is for the temperature coefficient.