Resistor Colour Code

Question

A carbon resistor carries coloured bands in the sequence yellow, violet, orange, and gold. What is its resistance together with the stated tolerance?

RankGuru · Accepted Answer

The colour code on a carbon resistor encodes its value: the first two bands give significant figures, the third band is a power-of-ten multiplier, and the fourth band gives tolerance, following the standard sequence where yellow = 4, violet = 7, orange = 3 (multiplier $10^3$), and gold = $\pm$5%. Reading the bands, the significant figures are 4 and 7, forming 47, and the multiplier $10^3$ scales this to $47 \times 10^3 = 47\,000\;\Omega = 47$ k$\Omega$, with a tolerance of $\pm$5%. The option 47 k$\Omega$ $\pm$10% wrongly reads the gold band as silver. The option 4.7 k$\Omega$ $\pm$5% uses a multiplier of $10^2$, misreading orange. The option 470 k$\Omega$ $\pm$5% overstates the multiplier as $10^4$. This follows the NCERT carbon-resistor colour-code convention. A plausibility check confirms the reading: orange firmly denotes $10^3$, so a 47 base value must land at 47 k$\Omega$, and the gold band reliably fixes the tolerance at $\pm$5%.

Resistor Colour Code

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