A circuit contains a 20 Ω resistor in series with a 5 Ω resistor connected to a 75 V supply. What is the current in the circuit?

A circuit contains a 20 Ω resistor in series with a 5 Ω resistor connected to a 75 V supply. What is the current in the circuit?

• A. 3 A
• B. 0.15 A
• C. 6 A
• D. 75 A

Answer: (A)

In a series circuit, the same current flows through each component, and the total resistance is the sum of the resistors. The two resistors add to 25 Ω, so with a 75 V supply the current is I = V/R = 75/25 = 3 A. Therefore, the circuit current is 3 amperes. The other values would require different total resistances (for example 0.15 A would need about 500 Ω total, 6 A would need about 12.5 Ω, and 75 A would need about 1 Ω), which doesn’t match the given 25 Ω total.

In a series circuit, the same current flows through each component, and the total resistance is the sum of the resistors. The two resistors add to 25 Ω, so with a 75 V supply the current is I = V/R = 75/25 = 3 A. Therefore, the circuit current is 3 amperes. The other values would require different total resistances (for example 0.15 A would need about 500 Ω total, 6 A would need about 12.5 Ω, and 75 A would need about 1 Ω), which doesn’t match the given 25 Ω total.