Automotive Electronics Practice Test

In a series circuit with three resistors of 4 ohms each, what is the source voltage based on the voltage drop across each resistor?

1. 8 volts

2. 10 volts

3. 12 volts

4. 16 volts

The correct answer is: 12 volts

In a series circuit, the total resistance is the sum of the individual resistances. In this case, there are three resistors, each with a resistance of 4 ohms. The total resistance can be calculated as: Total Resistance = 4 ohms + 4 ohms + 4 ohms = 12 ohms. When current flows through each resistor, the voltage drop across each resistor can be determined using Ohm's law, which states that V = I * R, where V is the voltage, I is the current, and R is the resistance. Assuming a constant current flows through the circuit, the voltage drop across each of the three resistors will be the same if they are identical. Therefore, if we denote the current in the circuit as I, the voltage drop across each resistor will be: Voltage Drop across one resistor = I * 4 ohms. Consequently, the total voltage drop across all three resistors together is: Total Voltage Drop = Voltage Drop across one resistor * 3 = I * 4 ohms * 3 = I * 12 ohms. This total voltage drop represents the source voltage applied across the entire series circuit. Thus, if the total voltage drop across the three