# Experiment: Ohmic Resistance and Ohm’s Law

Pages: 8 (1549 words) Published: September 17, 2008
Physics

Practical Report:

Experiment: Ohmic Resistance and Ohm’s Law

Patrick Doan
11 PHYS 71
12/9/08

1.0 Aim1
2.0 Hypothesis1
3.0 Materials1
4.0 Method 2
5.0 Results3
- 5.1 Qualitative Observations 3
- 5.2 Data 3-4
6.0 Discussion5
7.0 Conclusion 6
8.0 Bibliography 7
9.0 Acknowledgements 7

1.0 Aim:

To find out how current, voltage and resistance in a circuit are related, also to discover the relationship known as ‘Ohm’s Law’.

2.0 Hypothesis:

In this experiment, conductors are used. Conductors which obey Ohm’s Law are called Ohmic conductors. Thus, for an ohmic conductor, a graph of V (Voltage) verses I (Current) is a straight line passing through the origin. A conductor that does not obey Ohm’s Law is called a non-ohmic conductor. Ohm’s Law:

3.0 Materials:

Power Pack 12V
Voltmeter
Light bulb
9 Alligator clips
Ammeter
Test tube
Switch
Multimeter

Patrick Doan1
4.0 Method:

1.Collect all equipment and make sure the surface is clean and not wet 2.Wrap the nichrome wire around the test-tube to form a coil 3.Use the multimeter to measure the resistance of the light bulb 4.Connect the power pack to the power point but do not switch it on 5.Set up a series circuit with the ammeter, switch, nichrome wire resistor (Figure 1), light bulb (Figure 2) connected in a series and connect the voltmeter in parallel with the nichrome wire or light bulb resistor. Use two alligator clips as a switch 6.To begin, turn the power source to the lowest setting. Switch on the power and record the reading on the voltmeter and the ammeter 7.Switch the circuit off and allow for the nichrome wire or light bulb to cool 8.Increase the power supply setting by one and record the result from the ammeter and voltmeter 9.Continue to increase the power supply in steps of one until power supply is at its highest 10.Do this until four tables have been collected

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5.0 Results:

5.1 Qualitative Observations:

Many observations were made in the conducting of this experiment. When the power source was switched on the light bulb lighted up. The readings on the ammeter and the voltmeter went up as the power input went up. The resistance also becomes greater as the voltage and current is higher. On a low power setting the light bulb was dimmer than when it was on a high power setting. The same was for the nichrome wire; it was much cooler on a low power setting than on a higher power setting.

5.2 Data:

Nichrome Wire - Test 1
Power InputVoltage (V)Current (mA)Resistance (Ω)
A0.000.000.00
B1.000.1010.00
C2.250.1317.31
D2.500.1714.71
E3.000.2015.00
F4.500.2518.00
G5.450.3018.17

Nichrome Wire - Test 2
Power InputVoltage (V)Current (mA)Resistance (Ω)
A0.000.000.00
B0.750.107.50
C2.000.1315.38
D2.750.1716.18
E3.750.2018.75
F4.900.2519.60
G5.900.3019.67

Nichrome Wire - Test 3
Power InputVoltage (V)Current (mA)Resistance (Ω)
A0.000.000.00
B0.850.108.50
C1.950.1315.00
D2.700.1715.88
E3.400.2017.00
F4.650.2518.60
G5.750.3019.17

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Nichrome Wire - Test 4
Power InputVoltage (V)Current (mA)Resistance (Ω)
A0.000.000.00
B0.800.108.00
C2.250.1317.31
D2.650.1715.59
E3.500.2017.50
F4.780.2519.12
G5.930.3019.77

Light Bulb - Test 1
Power InputVoltage (V)Current (mA)Resistance (Ω)
A0.000.000.00
B1.000.1010.00
C2.000.1513.33
D3.500.2017.50
E5.000.2520.00
F6.500.2724.07
G8.000.3324.24

Light Bulb - Test 2
Power InputVoltage (V)Current (mA)Resistance (Ω)
A0.000.000.00
B1.000.1010.00
C...

Bibliography: Microsoft Encarta Encyclopedia Standard, 2005, CD ROM, Microsoft Corporation, U.S.A
9.0 Acknowledgements