Question

A resistor is marked with the rings coloured brown, black, green, and gold. The resistance in ohm is:
(A) $\left( {3.5 \times {{10}^5} \pm 5\% } \right)$
(B) $\left( {1.10 \times {{10}^5} \pm 10\% } \right)$
(C) $\left( {8 \times {{10}^6} \pm 5\% } \right)$
(D) $\left( {1 \times {{10}^6} \pm 5\% } \right)$

Answer 1

Hint: Resistor Colour Coding uses coloured bands to easily identify a resistors resistive value and its percentage tolerance. An international and universally accepted resistor colour code scheme was developed many years ago as a simple and quick way of identifying a resistor's ohmic value no matter what its size or condition. It consists of a set of individual coloured rings or bands in spectral order representing each digit of the resistors value.

Complete Step by Step Solution: According to the Resistor Colour Code system, the “left-hand” or the most significant coloured band is the band which is nearest to a connecting lead with the colour coded bands being read from left-to-right as follows:
\[{\text{Digit, Digit, Multiplier = Colour, Colour x 1}}{{\text{0}}^{{\text{colour}}}}\] in Ohms ($\Omega $)
The fourth and fifth bands are used to determine the percentage tolerance of the resistor. Resistor tolerance is a measure of the resistors variation from the specified resistive value and is a consequence of the manufacturing process and is expressed as a percentage of its “nominal” or preferred value.
Typical resistor tolerances for film resistors range from 1% to 10% while carbon resistors have tolerances up to 20%. Resistors with tolerances lower than 2% are called precision resistors with the or lower tolerance resistors being more expensive.
Most five band resistors are precision resistors with tolerances of either 1% or 2% while most of the four band resistors have tolerances of 5%, 10% and 20%. The colour code used to denote the tolerance rating of a resistor is given as:
Brown = 1%, Red = 2%, Gold = 5%, Silver = 10 %. If the resistor has no fourth tolerance band then the default tolerance would be at 20%.
It has been given that a resistor is marked with the rings coloured brown, black, green, and gold. The resistance is $\left( {1 \times {{10}^6} \pm 5\% } \right)$.

Hence, the correct answer is Option D.

Note: There are many different types of Resistor available which can be used in both electrical and electronic circuits to control the flow of current or to produce a voltage drop in many different ways. But in order to do this the actual resistor needs to have some form of “resistive” or “resistance” value. Resistors are available in a range of different resistance values from fractions of an Ohm ( $\Omega $ ) to millions of Ohms.
The resistance value, tolerance, and wattage rating are generally printed onto the body of the resistor as numbers or letters when the resistor's body is big enough to read the print, such as large power resistors. But when the resistor is small such as a $1/4$ watt carbon or film type, these specifications must be shown in some other manner as the print would be too small to read. So to overcome this, small resistors use coloured painted bands to indicate both their resistive value and their tolerance with the physical size of the resistor indicating its wattage rating. These coloured painted bands produce a system of identification generally known as a Resistors Colour Code.