Two resistors \( P \) and \( Q \) of \( 2 \Omega \) each are connected in a series. If \( 5 A \) current is flowing through resistor \( Q \), calculate the equivalent resistance and the voltage at which the resistors are connected. [Ans: \( 4 \Omega, 20 \mathrm{~V} \) ]

When resistors are connected in series, the equivalent resistance is simply the sum of the individual resistances. For resistors \( P \) and \( Q \) both having a resistance of \( 2 \Omega \), the equivalent resistance \( R \) is: \[ R = R_P + R_Q = 2 \Omega + 2 \Omega = 4 \Omega \] Now, to find the voltage across the resistors, we use Ohm's Law, \( V = I \times R \). With a current of \( 5 A \) flowing through the series circuit and the equivalent resistance of \( 4 \Omega \): \[ V = 5 A \times 4 \Omega = 20 \mathrm{~V} \] Thus, the equivalent resistance is \( 4 \Omega \) and the voltage is \( 20 \mathrm{~V} \). In series circuits, the current flowing through all components is the same, which simplifies calculations greatly! If you find that the current through one component doesn’t match the others, double-check your configuration. Accidental parallel connections can lead to that!