Download PHYSICS Ohm`s Law and Power Calculations OHMS WS I

Name _______________________________________________ Period ____ Date ____________
PHYSICS
Ohm's Law and Power Calculations
OHMS WS I
DIRECTIONS: Solve each of the following problems on your own paper. Show all variables,
formula, substitution and circle answer.
1. Garrett is going trick-or-treating for Halloween so he puts new batteries in his flashlight.
Until the batteries die, it draws 0.5A of current, allowing a total of 5400 C of charge to flow
through the circuit. How long will Garrett be able to use the flashlight before the batteries’
energy is depleted?
2. Compute the resistance of an electric heater if a current of 5.5 amps passes through the heater
that is connected to a house circuit providing 110 volts.
3. Compute the current in a circuit containing a 3-ohm resistor connected to a 6-volt source.
4. A total current of 4 amps flows through a 3-ohm resistor. What voltage was supplied to the
circuit?
5. A 3-volt battery supplies 0.5 amp through a resistor. Calculate the resistance in ohms.
6. A current of 0.25 amp flows through the filament of a light bulb connected to a 110-volt line.
Calculate the wattage of the bulb.
7. An electric motor operates on a 120-volt line and draws a current of 0.1 amps. What is the
power rating of the motor in watts? In kW?
8. A current of 2.0 amps flows through the filament of a 250-watt light bulb. What voltage is
being supplied to the line?
9. Compute the power rating of an electric toaster that draws a current of 10 amps from a 110volt line.
10. An electric iron with a 14-ohm heating element draws 9.0 amps of current from an unknown
voltage source. Calculate the power rating of the iron and then calculate the voltage supplied
to the iron by the line.
11. Tyler’s car radio will run from the 12V battery that produces a current of 0.2A even when the
car is turned off. The car battery will no longer operate when it has lost 1.2 x 106 J of energy.
If Tyler gets out of the car and leaves the radio on by mistake, how long will it take for the
car battery to go completely dead (that is, lose all energy)?
12. In your home the refrigerator is on 24 hrs a day. It has a power rating of 750W. If you pay
$0.15/KWH for electricity, how much will it cost to keep these items running for 30 days?
13. A 1000.-watt heater operates at 120 V. Calculate the current generated in 2.00 hour.
14. A charge of 8.4 C exerts a force of 5 x 10-3 N on a 1.6 C charge. How far apart are the
charges?
15. Two electrons are 0.06m apart. What is the electric force between the two electrons?