If one speaker is wired in a series circuit and another speaker is added into the same series, what happens to the volume?

• A. It increases
• B. It decreases
• C. It stays the same
• D. It fluctuates

Answer: (B)

In a series circuit, the same current flows through every component, and the total resistance is the sum of all resistances. Adding another speaker in series increases the total resistance the amplifier has to push current through. With a fixed supply voltage, that means the current drops (I = V / R_total). Since the power delivered to the speakers depends on the current and resistance (P = I^2R or P_total = V^2 / R_total), a higher total resistance reduces the power available to the speakers. If the speakers are similar, the voltage is divided between them, so each one gets less voltage and less power, making the overall volume lower. So the volume decreases when you add another speaker in series.