In a series circuit of resistors 4 Ω and 6 Ω connected to a 24 V source, what is the current?

• A. 4 A
• B. 2.4 A
• C. 6 A
• D. 1.2 A

Answer: (B)

In a series circuit, the same current flows through every component, and the total resistance is the sum of the individual resistances. Add the resistors: 4 Ω + 6 Ω = 10 Ω. Use Ohm’s law with the source: I = V / R = 24 V / 10 Ω = 2.4 A. That is the current through the circuit and through each resistor. The other values would require a different total resistance than 10 Ω, so they don’t fit this arrangement.