Download PROBLEM SET Current, Voltage, and Resistance

MYIB/HONORS PHYSICS
PROBLEM SET: Electric Current, Resistance, and Voltage
NAME:
Solve the following problems on another sheet of paper. All answers should be expressed in four significant digits
with correct units.
Electric Current, Ohm’s Law, and Power
1. (I)Five amperes of current is flowing through a point on a wire.
a. How many coulombs of charge flow by the point in 1 second?
b. How many coulombs of charge flow by the point in 5 seconds?
2. (I) If electric current flows in only one direction it is called _____ current. Current that changes
direction is called _____ current.
3. (I)In the United States alternating current changes direction _____ times a second, but in most
European countries alternating current changes direction _____ times a second.
4. (I) A resistance of 30 Ω is placed across a 90 V battery. What current flows?
5. (I) A motor with an operating resistance of 30 Ω is connected to a voltage source. The current in
the motor is 4.0 A. What is the voltage of the source?
6. (I) A transistor radio uses 0.2 A of current when it is operated by a 3 V battery. What is the
resistance of the radio?
7. (II)When a resistor R1 is connected to a voltage source, 3.0 A of current flows. The first resistor
R1 is disconnected from the source. When a second resistor R2, with a resistance of 1.5R1, is
connected to the voltage source, how much current will flow through R2?
8. (I) Electric current will always follow the path of _____ resistance. Therefore, as resistance
increases the current that flows _____ and as resistance decreases the current that flows ____.
9. (I) A current of 0.5 A flows through a lamp when it is connected to a 120 V source.
a. What is the resistance of the lamp?
b. What is the wattage of the lamp?
10. (I)A toaster uses 300 W of power. If the toaster is connected to a 110 V source, how much
current is flowing through the toaster?
11. (I) A 60 watt light bulb uses 1.55 A of current, what is the resistance of the bulb?
12. (II) A space heater with a resistance of 75 Ω is plugged into a 110 V source.
a. What current flows through the heater?
b. How much power is being dissipated by the heater?
c. How much energy will the heater use in 12 hours?
1)
a. 5.000 C
b. 25.00 C
5) 120.0 V
2) direct; alternating
3) 60; 50
4) 3.000 A
6) 15.00 Ω
7) 2.000 A
8) least; decreases; increases
9) a. 240.0 Ω
b. 60.00 W
10) 2.727 A
11) 24.97 Ω
12) a. 1.467 A
b. 161.4 W
c. 1937 Wh or 1.937 kWh