PHY2049 - GENERAL PHYSICS II
PRACTICE QUIZ 25

Below you will find a set of 5 conceptual and numerical revision questions selected randomly from lots of questions I have put together covering the material in Chapter 25, "Electric Current and Direct-Current Circuits". This includes questions on electrical current, resistance, Ohm's Law, energy in circuits, combinations of resistors, Kirchhoff's rules and R-C circuits. When you have finished the quiz, click on the "Submit Quiz" button at the bottom and within seconds it will be automatically graded and the results returned to you!

To select a new set of questions click on the "Reload" or "Refresh" button on your browser. You may find some of the questions duplicated but that's the nature of a random selection. Try it a few times ... it's not fattening and you may learn something!

Many thanks to Mark Wood for producing the quiz-maker code.


Q1: Wire A, which is of the same length and material as wire B, has half the diameter of wire B. If the resistance of wire B is R, what is the resistance of wire A?

R
2R
R/2
4R
R/4

Q2: Three resistances are connected as shown in the figure. The potential difference between points A and B is 26 V.

How much current flows through the 2 Ω resistance?

2 A
4 A
6 A
8.7 A
10 A


Q3: A 0.120 μF capacitor, initially uncharged, is connected in series with a 10.0 × 103 Ω resistor and a 12.0 V battery of negligible internal resistance. Approximately how long does it take the capacitor to reach 90% of its final charge?

5.5 ms
2.8 ms
1.4 ms
3.5 ms
6.9 ms

Q4: An uncharged capacitor and a resistor are connected in series to a battery as shown below.

If E = 15 V, C = 20 μF, and R = 4.0 × 105 Ω, the time constant of the circuit is approximately

10 s
8.0 s
19 s
4.0 s
2.5 s


Q5: The figure shows a simple RC circuit consisting of a 100.0 V battery in series with a 10.0 μF capacitor and a resistor. Initially, the switch S is open and the capacitor is uncharged. Two seconds after the switch is closed, the voltage across the resistor is 37 V.

How much charge is on the capacitor 2.0 s after the switch is closed?

1.1 × 10-3 C
2.9 × 10-3 C
3.7 × 10-4 C
5.2 × 10-4 C
6.6 × 10-4 C


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