Jr. High Tech. Assignment 2 – Measuring Energy (Part 1)
Power = Current (I) x Voltage (V),
Measurements
Power - Watts, Current – Amps, and Voltage – Volts
P  IxV
Use the interactive website:
http://phet.colorado.edu/en/simulation/circuit-construction-kit-dc-virtual-lab
Activity 1.
Create a complete circuit and use the meters to measure the current and the voltage being used by a
small bulb . Complete several different circuits using more than one battery and notice how the voltage
and current change.
As you add more batteries the Voltage________________ and Current ____________________
As you add more bulbs the Voltage _________________ and Current _____________________
Build a circuit with 1 bulb and 2 batteries. Connect an ammeter and voltmeter to measure values for
current and voltage. Use these values calculate the power of the bulb using the formula above.
Problem # 1: You have an electric heater in your room. If it operates at 220 volts and consumes 10
amps of electricity, what is its power rating?
Activity 2
Energy = current × voltage × time
A) Suppose the heater in problem #1 was on for 12 hrs, how much energy would it consume? Use
the formula for energy to find out.
B) If electricity costs $0.11 per kilowatt hour, how much would it cost to run the heater for 12
hours. (hint: You must divide the amount of power by 1000 and then multiply by 0.11)
Problem 2: A heater installed in a garage consumes 27 A and 220V of electricity?
A) How much power is the heater using?
B)
How much would it cost to operate the heater for 8 hours if electricity cost $0.11 per
kilowatt hour?
Activity #3
Working with your group, use a multi-meter to test the batteries given to you by your teacher. Be sure
you have the meter on direct voltage. Classify the batteries as strong, average or weak. Record the
voltage and diagnosis of the battery in the table below. Discard any weak batteries by giving them to
the teacher. For AA batteries…above 1.4v is strong, 1.0-1.4v is average, and below 1.0v is weak.
Battery Type
9V or AA
Voltage
Strong
Average
Weak