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The drawing shows a circuit that contains a battery, two resistors, and a switch. Consider the circuit with R1 = 66.9, R2 = 102.6, and V = 10.0.
(a) What is the equivalent resistance of the circuit when the switch is open and closed?
(b) What is the total power delivered to the resistors when the switch is open and closed?
The drawing shows a circuit that contains a battery, two resistors, and a switch. Consider the circuit with R1 = 66.9, R2 = 102.6, and V = 10.0.
(a) What is the equivalent resistance of the circuit when the switch is open and closed?
(b) What is the total power delivered to the resistors when the switch is open and closed?
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a) in general, in the open switch, we can ignore the R2 resistor. Thus, the only important resistance is the one on R1. Thus, the open circuit's ER = 66.9 ohms.
In the closed case, both the resistors are key. Resistors that are wired as such in a branching method are in parallel. The formula in this case to use is 1/(Ceq) = 1/(R1) + 1/(R2) . Solving for Ceq = 1/ (1/(R1) + 1/(R2)). I am getting about 40.495 ohms.
b) The formula for power across a resistor where V is known is P=V^2/R. Using our previous answers, we plug and chug:
Open: P = 100/66.9 = 1.49477
Closed: P = 100/40.495 = 2.46944
wikipedia has all the key formulas that are key in these questions. Best to memorize them
In the closed case, both the resistors are key. Resistors that are wired as such in a branching method are in parallel. The formula in this case to use is 1/(Ceq) = 1/(R1) + 1/(R2) . Solving for Ceq = 1/ (1/(R1) + 1/(R2)). I am getting about 40.495 ohms.
b) The formula for power across a resistor where V is known is P=V^2/R. Using our previous answers, we plug and chug:
Open: P = 100/66.9 = 1.49477
Closed: P = 100/40.495 = 2.46944
wikipedia has all the key formulas that are key in these questions. Best to memorize them