Question

The colour code of a carbon resistor is, Brown, Black, Brown and Red. The value of the resistor is?

• A. $10\Omega \pm 5\%$
• B. $1k\Omega \pm 2\%$
• C. $100\Omega \pm 2\%$
• D. $10\Omega \pm 2\%$

Answer 1

The correct option is C $100\Omega \pm 2\%$

According to the colour code, brown colour stands for $1$, black for $0$ and red for $2$.
First and second band represents the first and second significant number respectively.
So, it is $10\Omega$.
Third band represents power of $10$ by which it is raised, so it is ${10}^1$.
Last band represents the tolerance of resistor, so it is $2$%.
Thus value of resistance, $R=(10\times {10}^1)\Omega \pm 2$% $=100\Omega \pm 2$%