posted by Anonymous .
Three wire-wound resistors have the following values: 30 ohms, 80 ohms, and 100 ohms. Each resistor has a voltage rating of 100V. If these three resistors are connected in series, can they be connected to a 240V circuit without damage to the resistors? Explain your answer.
please help and thank you
total R = 210 ohms, so current is 240/210 = 8/7 amps
E=IR so if any R is over 100*7/8=87.5Ω it will experience a voltage drop of over 100V.
E = 240 Volts
R1 = 30 Ohms
R2 = 80 Ohms
R3 = 100 Ohms
I = E/(R1+R2+R3) = 240/210 = 1.143A
V1 = I*R1 = 1.143 * 30 = 34.3 V.
V2 = I*R2 = 1.143 * 80 = 91.4 V.
V3 = I*R3 = 1.143 * 100 = 114.3 V.
The voltage across R3 is higher than the rated voltage.