A 100 ohm 1 watt resistor and 800 ohm 2 watt resistor are connected in seriesmaximum dc output voltage that can be applie continuously to series circuit without exceeding power limit of resistor?

Answer 1

If a 100 ohm 1 watt resistor and an 800 ohm 2 watt resistor are connected in series, the maximum DC voltage that can be applied without exceeding the power limit of both resistors is 45 volts.

Start with power rule and ohm's law...

P = IE

E = IR

so

P = I2R

solve for current

I2 = P/R

I = (P/R)0.5

determine current at max power for each resistor R1 = 100, R2 = 800

I1 = (1/100)0.5 = 0.1 amperes

I2 = (2/800)0.5 = 0.05 amperes

The limiting resistor is R2, so calculate voltage of both at current flow of I2

V1+2 = (0.05)(900) = 45 volts