DC Circuit Quiz

hard 5 Questions
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Question 1 of 5

In a series RC circuit, the voltage across the capacitor at time t=0 after the switch is closed is:

At t=0, capacitor acts like a short circuit, and the voltage across it is zero.
Question 2 of 5

What is the Thevenin equivalent resistance (Rth) of a circuit composed of a 10V voltage source in series with a 2? resistor, and a parallel branch containing a 4? and a 8? resistor (in series)?

Short-circuiting the voltage source, the equivalent resistance is calculated as 2? + (4? // 8?) = 2 + (4*8)/(4+8) = 2.67?
Question 3 of 5

If a 12V battery is connected across three resistors in parallel: 3?, 6?, and 9?, what is the total current flowing through the circuit?

Calculate individual currents and sum them up. I=V/R, I1=12/3=4A, I2=12/6=2A, I3=12/9=1.33A. Total=4+2+1.33=7A (approx.)
Question 4 of 5

In a Wheatstone bridge circuit, when the bridge is balanced, the voltage difference between points B and D (using standard nomenclature) is:

When the bridge is balanced, the potential at B and D are equal, and there's no potential difference.
Question 5 of 5

What is the time constant (?) of an RL circuit with a 10 mH inductor and a 1 k? resistor?

? = L/R = 10 mH / 1 k? = 10 x 10^-3 / 1000 = 10 x 10^-6 = 10 ?s
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