Download Electricity Lab (Teachers Edition)

Name: ________________________________
Per: _______ Date: ___________________
Electricity Lab1 (Teachers Edition)
Question for this Investigation:
How does electricity work inside our electronics?
Materials2:
 6-10 wires with “alligator” clips on ends
 2 battery holders
 3 light bulbs in holders



2 knife switches
2 “D” batteries
Digital Multimeter
Procedure:
1. Build the circuit shown in the diagram with one battery, a switch, and a bulb.
Questions!
1. How can you tell the electric current is flowing in the circuit? Can you see the current
flow?
The lightbulb turns on. No.
2. How does the switch cause current to stop flowing? How can you tell?
It breaks the circuit. The lightbulb turns off.
3. What do you think will happen if you flip the battery around?
(It can be whatever they say.)
4. Try it! Was your prediction correct? What changed in the circuit once you switched the
battery around?
Something about how the current can still flow, maybe backwards.
Electric En
(wires)
5. Draw a diagram of the direction energy flows through the circuit. Label the forms of
energy that appear.
Chemical Energy
1
Modified from Hsu, Tom. Investigations: Physics, A First Course. CPO Science. Peabody, MA. 2005. pp.57-68.
These are the basic components of Hsu’s Electric Circuits kit without the potentiometer, other components, and some
extra lightbulbs. If you have the funds, buying the kit from CPO is a great (and easier) idea than assembling all this
yourself.
2
Rad
Hea
2. Circuit diagrams are used to simplify drawing electric circuits. In a circuit diagram, wires
are solid lines and other electric devices have their own symbols. In the space below, draw
a circuit diagram of the circuit you just made in step 1. You will not use all the symbols in
the table.
Battery
Resistor
Cell
Wires
Light bulb
Switch
3. Make your circuit! Go ahead and try building a new circuit of your own design. Once
you make one that works, draw its circuit diagram below. Use the correct symbols!
Questions!
1. When you created your own circuit did it work the first time you tried
connecting everything? What do you think was the most important thing that
caused it to work?
No. I actually connected all the parts to circuit and then
It worked.
4. What is the use of a battery? A battery acts as a power source to push electrons around a
circuit and thus, creates electricity. The battery’s strength is called voltage and measured in
Volts (V). Find the voltage written on your battery and write it down here: _1.5 V____
To check the real voltage of your battery, use the
digital multimeter to test it. Set the dial to DC Volts
(V—) 2V. The red lead goes to the positive terminal
and black to the negative. Touch two points in a
circuit with the leads and the meter reads the
voltage between the two points.
Questions!
1. Make a prediction for what will happen if you add another battery to your
circuit.
Any answer will do but specifically, it will increase the
light output in the bulb.
2. Now take a second battery and place it in the circuit “end to end” with the first
battery. Make sure that they are connected + to -, otherwise your circuit will not
work. Was your prediction correct? Describe any changes in the circuit that you
observe.
Yes, the light bulb got brighter.
5. Measuring voltages. Using a working circuit and the digital multimeter, try measuring the
voltages “across” different objects (wires, light bulbs, switches). When we say “across” we
mean placing a multimeter lead on the metal on one of side of an object and the other lead
on the other side. Write down the measurements you get in the table below.
Object
Voltage (V)
Lightbulb
1.38 V
Wire
0
Switch
0
Question!
1. Do you notice anything significant about the voltages of the objects in the
circuit?
They all add up to the voltage of the battery!
6. What is electric current? If your circuit is not is not in the original configuration, please
remake it to that now (procedure step 1). Leave the switch open so no electricity is flowing.
Also, turn the dial of the multimeter to DC A (A—) at about 100 mA, which means direct
current measured in milliAmperes.
Remember, electric current is the amount electrons flowing in a circuit over time. To
measure it, the multimeter must be connected so the current has to flow though it only. No
other path may allow the current to bypass the multimeter. You know you are doing this
correctly if the light bulb lights up only when you measure with the multimeter.
Questions!
1. How much current is flowing in the circuit when the bulb is making light?
Between 50 - 200 mA
2. In physics, we say current flows from the positive terminal of a battery or power
source to the negative end. Return to your first circuit diagram you drew and
draw arrows around the circuit showing the direction of current flow.
See above.
Conclusions
1. Though our favorite electronics are much more complicated than the circuits we just made,
there are some similarities. Describe at least two of those similarities.
These circuits are similar to my electronics in that they both use batteries and they
both have wires. They also both have pieces that use electricity for something.
Extra Credit (5 points)
1. Create your own circuit (or remake the one you made in step 3) and draw its circuit diagram
below (if you’re doing the one from step 3 you do not have to redraw it). Measure the voltages
across different objects and the current flowing through the circuit. Make tables like the ones in
the lab to show your data.
We just used our circuit drawing in part 3.
Object
Voltage (V)
Current: 86 mA
Lightbulb
1.38
Lightbulb
1.35
2 batteries
2.7