What Is the Maximum Voltage for a Circuit with Series and Parallel Resistors?

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SUMMARY

The maximum voltage for a circuit with a 2.7 kOhm and a 3.8 kOhm resistor connected in parallel, which is then connected in series with a 1.5 kOhm resistor, is determined by the power rating of each resistor. Each resistor is rated at 0.9 W. To find the maximum voltage, first calculate the equivalent resistance of the parallel resistors and then the total resistance in series. The formulas used include \( V = I \times R_{eq} \) and \( I = \sqrt{\frac{P}{R}} \) for each resistor to ensure the power dissipation does not exceed 0.9 W.

PREREQUISITES
  • Understanding of Ohm's Law and power calculations
  • Knowledge of series and parallel resistor combinations
  • Familiarity with equivalent resistance calculations
  • Basic algebra for manipulating equations
NEXT STEPS
  • Calculate the equivalent resistance for parallel resistors using \( \frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} \)
  • Learn how to apply Ohm's Law to find current and voltage in circuits
  • Explore power dissipation in resistors and its implications on circuit design
  • Study the effects of resistor ratings on circuit performance and safety
USEFUL FOR

Electrical engineering students, hobbyists designing circuits, and anyone involved in circuit analysis and design will benefit from this discussion.

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Homework Statement



A 2.7 kOhms and a 3.8 kOhms resistor are connected in parallel; this combination is connected in series with a 1.5 kOhms resistor.
If each resistor is rated at 0.9 W (maximum without overheating), what is the maximum voltage that can be applied across the whole network?

Homework Equations



parallel resistors 1/Req = 1/R1 + 1/R2 + 1/R3 ...
resistors in a series Req = R1 + R2 + R3 +...
Vab = E- IR
I= V/Req

The Attempt at a Solution



i have no idea. please help!
 
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Using the formula for wattage
w = I^2*R, find the current in resistance in series.
This is the current drawn from the battery.
Using this current, check the wattage of the individual resistance in the parallel combination. If it is less than 0.9 W, proceed further to find the total resistance of the circuit. Then V = I*Req.
If not, find the current in the individual resistance in the parallel combination for 0.9 w dissipation. Take the minimum current for finding the maximum voltage supply.
 

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