PSC 1121 - Exam IV
1. Calculate the force between a balloon charged with 4x10-3 C and a steel sphere charged with 8x10-2 C if they are placed 0.035 m apart.
Answer: 2.35x109 N
2. Calculate the force between a pencil charged with 6x10-4 C and a piece of paper charged with 3x10-3 C if they are placed 0.155 m apart.
Answer: 6.74 x105 N
3. Three stereo speakers with resistances of 220, 440 and 660 ohms are connected in parallel across a 110 Volt line.
a) What is their combined resistance?
Answer: 120 W
b) What total current is drawn by the three speakers?
Answer: 0.916 A
4. Three light bulbs each with a resistance of 24, 36 and 48 ohms are connected in parallel across a 220 Volt line.
a) What is their combined resistance?
Answer: 11.077 W
b) What total current is drawn by the three speakers?
Answer: 19.87 A
5. Three coils with resistances of 5, 10, and 15 ohms are connected in series.
a) What is the total resistance of the combination of resistors?
Answer: 30 W
b) If a voltage of 20 volts is maintained across the group, how much current will flow?
Answer: 0.667 A
6. Three electrical appliances with resistances of 20, 40, and 55 ohms are connected in series.
a) What is the total resistance of the combination of resistors?
Answer: 115 W
b) If a voltage of 40 volts is maintained across the group, how much current will flow?
Answer: 0.348 A