Case: Read the following passage and answer accordingly.
The current through a single resistor R across which there is a potential difference V is given by Ohm’s law \( I=V/R \). Resistors are sometimes joined together and there are simple rules for the calculation of equivalent resistance of such a combination. Two resistors are said to be in series if only one of their endpoints is joined. Two or more resistors are said to be in parallel if one end of all the resistors is joined together and similarly the other ends joined together.
What will be the effective resistance if four resistors of resistance \( 2.5\,\Omega \), \( 3.5\,\Omega \), \( 4\,\Omega \) and \( 12\,\Omega \) are connected in series?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → \( 22\,\Omega \)
For resistors in series, the same current flows through each and the voltages add, so the equivalent resistance is the sum of the individual resistances.
\( \begin{aligned} R_{\mathrm{eq}} &= R_1+R_2+R_3+R_4 \\ &= (2.5+3.5+4+12)\,\Omega \\ &= 22\,\Omega \end{aligned} \)