What is the total power of 4 quarter watt resistors wired in series?

• A. ¼ Watt
• B. 1/16 Watt
• C. 4 Watt
• D. 1 Watt

Answer: (D)

Power ratings are about safe dissipation. When four identical quarter-watt resistors are connected in series, the same current flows through each, and the total safe dissipation is the sum of the individual ratings. Since each resistor can handle 0.25 W, four of them in series can safely dissipate 4 × 0.25 W = 1 W, assuming they share the heat roughly equally (which they do when the resistors have equal resistance). So the total power rating of the string is 1 W. The other numbers would not reflect this additive property: a single resistor is 0.25 W, not the whole chain; 1/16 W is far too small for four elements; and 4 W would require each element to dissipate 1 W, which exceeds its rating.