Question

Three resistors are connected in series across a 15-V power supply. If the potential drops across resistors 1 and 2 are 4.1 volts and 3.1 volts, what is the exact potential drop (in volts) across resistor 3?

Answer 1

Answer:

7.8 V

Explanation:

When resistors are connected in series, they are connected in the same branch of the circuit. This means that the current flowing each resistor is the same, while the sum of the voltage drops across each resistor is equal to the potential difference of the power supply:

$V= V_1 + V_2 + V_3$

In this circuit we have:

V = 15 V

$V_1 = 4.1 V$

$V_2 = 3.1 V$

So, the voltage drop across resistor 3 is

$V_3 = V-V_1 - V_2 = 15 V - 4.1 V - 3.1 V=7.8 V$