Circuits and Magnetic Fields Practice Test

1.  Consider the following simple circuit with three identical light bulbs for resistors.

A)  Will the three bulbs be identically bright? Briefly explain.

B)  Now unscrew bulb R2. (There is now a break in the circuit where R2 was.)

i.  What happens to the current through the battery when R2 is unscrewed?

(increases/decreases/remains constant) Explain.

ii.  What happens to the brightness of bulb R3?

(increases/decreases/remains constant) Explain.

iii.  What happens to the brightness of bulb R1?

(increases/decreases/remains constant)

2.  Three identical bulbs and an uncharged capacitor. At t = 0, the switch is closed.

A) Explain the relative brightness of the bulbs at t = 0.

B) As time goes on, how does the brightness of bulb 1 change? Why?

3.

V / I / R
1 / 6 W
2 / 2 A

4.

5.  What does it mean to say that two elements of a circuit are in parallel?

6.  What does it mean to say that two elements of a circuit are in series?

7.

V / I / R
1 / 8 A
2 / ¼ Ω
3 / 4 A
4 / 1 Ω
V / I / R
1 / 5 Ω
2 / 10 A
3 / 5 Ω
4
5 / 4 Ω

8.

9. The following is the oscilloscope tracing of the voltage across a capacitor in an RC circuit driven by a square wave function generator.

Scale: Vertical 1 div = 5.0 mV Horizontal: 1 div = 2.0 ms

A) What is the peak-to-peak voltage across the capacitor?

B) Estimate the time constant t.

C) If the value of the resistor is 2.2 mega-ohms, what is the value of the capacitor?

10. An electron is accelerated from rest through an 8200 V potential, where it enters into a uniform magnetic field B that is perpendicular to the motion of the electron as shown. The region of uniform magnetic field is

2.0 cm across. Find B.

11. Do problem 51 on page 832 from your text. Make sure you read 28-7.

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