Experiment 8.3: Voltage and Electric Current (P.110-111)
Objective:
To study the relationship of the number of dry
cells, voltage
of the dry cells and the electric in the circuit.
Procedures:
1. Measure the voltage of one dry cell using a voltmeter as shown below on
the left. Record the reading of the voltmeter.
2. Disconnect the voltmeter. Set up the circuit shown on the right using
the same dry cell as in step 1.
3. Close the switch. Record the reading of the ammeter and the brightness
of the bulb.
4. Repeat steps 1 to 3 using two
dry cells. Make sure the two dry cells are connected in the same direction.
5. Repeat steps 1 to 3 using three
dry cells.
Results:
|
Number
of dry cells
|
Voltage
(V)
|
Electric
current (A)
|
Brightness
of the bulb
(arbitrary
unit)*
|
|
0
|
0
|
0
|
-
|
|
1
|
0.5
|
0.15
|
+
|
|
2
|
1
|
0.25
|
++
|
|
3
|
1.5
|
0.3
|
+++
|
*Brightness of the bulb can be represented by the number
of “+”
Plot a graph to show the relationship between the
total voltage of the dry cells and the electric current of the circuit.
Discussion:
When more dry cells are
connected in the same direction, the total voltage is higher.
The electric current flowing through the circuit is
larger,
so the bulb is brighter.
Conclusion:
The more the cell dry
cells are connected in the same direction, the higher the voltage and
the larger the electric current flowing through the circuit.
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