Aim:
- To find out the voltage in
series and parallel circuit
- To observe the resistance in
different types of circuit (parallel and series)
- To construct an electrical
circuit and to be able to use volltmeters. ammeters to take reading and to
provide reasons to explain the measurements in circuits
Hypothesis:
- The voltage in parallel circuit is equal across all the components in
the circuit, while the voltage in series circuit is the sum of the voltage
across each of the electrical components in the circuit.
- The resistance in a parallel circuit is 1/R= 1 / R1 + 1 / R2
+ 1 / R3 +.... While the resistance in a series circuit is R= R1
+ R2 + R3 +….
- When electric circuits are arrange differently then the current and
voltage will be different as well.
Theory Background:
Voltage is an electrical potential difference. It is
the potential energy that makes the electrical current flow in a circuit by
pushing the electrons around. The unit of voltage is volt (V). We can form an
electric circuit by connecting the components that have different electrical
properties. Voltage in parallel circuit is equal across all the components in
the circuit. Electric circuits are like our blood circulatory system.
Manipulative Variables:
Independent:
- The type of circuit
- Voltage and Current
- The types of circuit
Controlled:
- Battery, Voltage,
- Voltage
- The amount of resistors
Dependent:
- Voltage, Brightness,
resistance
- Resistance
- Current
Materials:
- Simulation
- Battery
- Amperemeter
- Wire
- Switch
Method:
1.
- Go to PHeT web site and use the Circuit Construction kit simulation
- Drag 3 batteries and measure the voltage using the voltmeter
2.
- Use the Circuit Construction
Kit simulation to build a circuit with a battery and a light bulb in the
Lifelike visual mode
3.
- Use CCK to build the circuits of Figure 1, 2, and 3 with a battery at
12 volts and light bulbs.
- Turn on the voltmeter and ammeter to measure voltage of the battery
and current
- Record bulb brightness
4.
- Repeat the procedure of (3)
for these figures
5.
- Use CCK to build the circuit
like below:
- Vary the voltage of the
battery
- Record the battery voltage
and the current in the circuit
6.
- Use CCK to build the circuit
like below:
- Vary the value of resistor
- Record in a data table
7.
·
Construct figure 1 using CCK
·
Make the resistors have different values
·
Use ammeter and voltmeter to measure current and voltage in some points
·
Calculate R using Ohms law for the total resistance
·
Repeat the steps for this figure:
8.
- Build the circuit like
Figure A
- Measure the voltage across
each resistor and the power supply. Also measure the current through each
resistor and the total current coming out the power supply.
- Repeat the steps using the
circuit like Figure B
Data Collection:
1. Observing voltage relationships
Battery
|
Voltage
|
1
|
1.5 V
|
2
|
1.5 V
|
3
|
1.5 V
|
1+2
|
3 V
|
1+2+3
|
4.5 V
|
2. Using voltage
Our design:
3. Using voltage in series circuits
Number of bulbs
|
Bulb ohm
|
Battery voltage
|
Current into
battery
|
Brightness of bulb
|
1
|
10 Ω
|
12 V
|
1.2 A
|
Bright
|
2
|
20 Ω
|
12 V
|
0.6 A
|
Medium
|
3
|
30 Ω
|
12 V
|
0.4 A
|
Low
|
4. Using voltage in parallel circuits
Number
of bulbs
|
Bulb
Ohm
|
Battery
Voltage
|
Current
into battery
|
Brightness
of bulb
|
1
|
10 Ω
|
12 V
|
1.2 A
|
Bright
|
2
|
5 Ω
|
12 V
|
2.4 A
|
Bright
|
3
|
3.3 Ω
|
12 V
|
3.6 A
|
Bright
|
5. Observing voltage and current relationshops
with resistors
Voltage
|
Current
|
Resistance
|
9 V
|
0.9 A
|
10 Ω
|
12 V
|
1.2 A
|
10 Ω
|
6. Observing voltage and current relationships
for variable resistors
Voltage
|
Current
|
Resistance
|
12 V
|
1.09 A
|
11 Ω
|
12 V
|
1.00 A
|
12 Ω
|
12 V
|
0.92 A
|
13 Ω
|
12 V
|
0.86 A
|
14 Ω
|
12 V
|
0.8 A
|
15 Ω
|
12 V
|
0.75 A
|
16 Ω
|
12 V
|
0.71 A
|
17 Ω
|
12 V
|
0.67 A
|
18 Ω
|
12 V
|
0.63 A
|
19 Ω
|
12 V
|
0.6 A
|
20 Ω
|
7.
Series: Battery – 10 V
Resistor
|
Voltage (V)
|
Current (A)
|
Resistance (Ω)
|
1
|
2.22
|
0.22
|
10
|
2
|
3.33
|
0.22
|
15
|
3
|
4.44
|
0.22
|
20
|
Total
|
9.99 V
|
0.22 A
|
45.45 Ω
|
Parallel: Battery = 10 V
Resistor
|
Voltage (V)
|
Current (A)
|
Resistance (Ω)
|
1
|
10
|
1
|
10
|
2
|
10
|
0.67
|
15
|
3
|
10
|
0.50
|
20
|
Left current
|
2.17
|
||
Total
|
10 V
|
4.34 A
|
2,304
|
8.
Figure A - Battery: 10 V
Resistor
|
Individual Resistance (ohms)
|
Current (amps)
|
Voltage (Volts)
|
Resistance in Circuit
|
1
|
10
|
0.67
|
6.67
|
6.67/0.67= 10
|
2
|
10
|
0.33
|
3.33
|
3.33/0.33 =10
|
3
|
10
|
0.33
|
3.33
|
3.33/0.33 = 10
|
Total
|
1.33 A
|
13.33 V
|
30
|
Figure B- Battery: 10 V
Resistor
|
Individual Resistance (ohms)
|
Current (amps)
|
Voltage (Volts)
|
Resistance in Circuit
|
1
|
10
|
0.5
|
5
|
5/0.5 = 10
|
2
|
10
|
0.5
|
5
|
5/0.5 =10
|
3
|
10
|
1.00
|
10
|
10/1 = 10
|
Total
|
1.85
|
18.5
|
30
|
Data Processing:
Analysis:
Battery
1 to battery 3 has the same voltage, and at the 4th column,
the voltage suddenly rises to 3V, it happens because battery 1 and 2 are being
add to each other, and the same thing also happens in the 5th
column. The number of the batteries changes to determine
the relationship. The voltage of the light bulb is bigger than the voltage of
the battery.Vary the voltage of the battery and write observations about how
the brigthness is affected by the voltage. The
voltage of the battery affects the brightness of the light bulb.We observe that, when the bulb has the resistance of 10,20
and 30 ohm’s, the battery voltage is still 12 Volt, but the current inside the
battery is different, and the brightness is also different, when when the
bulb has the resistance of 10 ohm, the current is 1,2 A which is bright, when
it has 20 ohm, the current is 0,6 A which is medium and when the resistance is
30 ohm, the current is 0,4 A which is low or not bright. The change of the
Voltage affects to the current as well. I= V/R and V=I x R.
It
is related because it has the same resistance in circuit even though it has
different power supply.
Conclusion:
- the voltage rises because
the batery were add to each other.
- the voltage of the light
bulb is bigger than the voltage of the battery but the voltage of
the battery affects the brightness of the light bulb.
- even though the resistance
of the bulb is diffferent, the battery voltage is the same, and the bulb
which has the smallest resistance is the brightest
5. when the
voltage change, the current also changes
7. even though it has
different power supply, we can stilll have the same resistance in circuit.
Resources:
- http://phet.colorado.edu/en/simulation/circuit-construction-kit-dc
- http://www.allaboutcircuits.com/vol_1/chpt_2/1.html
-Shannisya, Naomi,
Andra, Ibram
10 Centaurus
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