Download Demo Activity: Understanding Circuits Series Circuit: 1. Build the

Demo Activity: Understanding Circuits
Series Circuit:
1. Build the series circuit shown:
2. What do the blue dots represent?
- The blue dots are showing the flow of electricity in the circuit.
3. From which end of the batteries are the blue dots flowing? Is this the (-) or (+) end?
- It is flowing from the grey end of the battery which is the negative end.
4. What happens if the switch is opened?
- The electricity stops flowing through the circuit as there is a break in it. Switch is acting as
the greatest resistor.
5. Collect the voltmeter, what does it measure? What are the units?
- Measures the voltage. Its units are volts (V).
6. Look at how you can manipulate the voltage: Measure the volts in the battery and then add
another battery, check the volts and see if there is any difference to the bulb’s brightness.
- The voltage of the single battery is 9 volts, the voltage of the 2 batteries is 18 volts (double
the amount). The light bulb also becomes much brighter.
So….. The greater the voltage the brighter the light bulb!
7. What does an ammeter measure? What are the units of this?
- It measures the amount of current (electric potential) and uses the unit of ampres (A).
8. Add an ammeter in the wire between the battery and light bulb. What is the measurement?
- The measurement is 1.80 A.
9. What happens to the current when you remove one of the batteries?
- It drops the current to 0.9 A, ½ the amount.
So……. The greater the voltage the greater the current in the circuit.
10. Click on the “show values” box and look to see what resistance there is in the circuit.
- The light bulb has a resistance of 10 ohms.
11. Add a second light bulb to the circuit. What does this do to the amount of resistance within the
circuit as well as the current? Is the light bulb brighter or not?
-
The resistance is doubled and the current has slowed down to 0.45 A (1/2 the value again)
causing the light bulb to become less bright.
So……. The greater the resistance the lesser the current.
12. What happens to the amount of current and resistance if we add another battery (or more
voltage)? What happens to the light bulb?
- The current doubles to 0.90 A and is moving through the circuit faster, the resistance stays
the same and the light bulbs become brighter.
13. Create the parallel circuit shown: Are the bulbs brighter or less bright than the ones in the
series circuit? Why do you think the brightness is different?
- They are brighter because there is easier/multiple pathways for the current to move.
14. Hook the ammeter up, what does it read, compare this to the series circuit.
- It reads 1.8 A. It has the same current measurement as the series circuit with one light bulb
and 2 batteries.
15. What are some things that affect the brightness of the light bulb(s) in a circuit?
- The more batteries (voltage) the brighter the bulbs.
- The less bulbs (resistance) in a series circuit the brighter the bulb.
16. When is a series circuit beneficial? Give an example of a series circuit that you are familiar
with.
- In Christmas lights, the bulbs are all in series. When it is okay that one load is dependent
upon another.
17. When is a parallel circuit beneficial? Give an example of a parallel circuit that you are familiar
with.
- A parallel circuit is beneficial when your load can not be dependent on others. In your
home, all appliances are in parallel to the main power source.