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DET103
ELECTRIC CIRCUIT FUNDAMENTAL 1
EXPERIMENT 2
OHM’S LAW
OBJECTIVES
1. To learn the relationship among R, V and I.
2. To experimentally prove the mathematical relationship among R, V and I.
INTRODUCTION
Ohm’s law defines that voltage is proportional to the current and vice versa. The circuit
current is inversely proportional to the resistance R. Both current and voltage have a linear
relationship with resistance remain constant.
The three forms of Ohm’s Law are,
V  IR , I 
V
V
, and R 
R
I
EQUIPMENT AND PARTS
Digital Multimeter
DC Power Supply
Resistor : 1k-2 unit
PROCEDURE
1. Measure the resistance of the 1kΩ resistor. Record this value in Table 1.
2. Connect the circuit shown in Figure 1.
Figure 1
3. Adjust the power supply for a 10 V output as measured by the digital multimeter.
Record this value in Table 1.
4. Measure the circuit current and record it in Table 1.
5. Using the measure values for V, R and I calculate V, R and I by using Ohm’s Law.
Record the calculated values in Table 1.
KOLEJ UNIVERSITI KEJURUTERAAN UTARA MALAYSIA
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DET103
ELECTRIC CIRCUIT FUNDAMENTAL 1
6. Repeat steps 1 through 5 with the power supply set to 20 V. Record all measurements
and calculations in Table 2.
7. Repeat steps 1 through 5 for the circuit of Figure 2. Record all measurements and
calculations in Table 3. When you are measuring V, measure across both resistors.
Figure 2
RESULTS
V
Measured values
R
I
Calculated Values
I=V/R
V=IxR
R=V/I
Calculated Values
I=V/R
V=IxR
R=V/I
Calculated Values
I=V/R
V=IxR
R=V/I
Table 1
V
Measured values
R
I
Table 2
V
Measured values
R
I
Table 3
KOLEJ UNIVERSITI KEJURUTERAAN UTARA MALAYSIA
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DET103
ELECTRIC CIRCUIT FUNDAMENTAL 1
EVALUATION QUESTIONS
1. How do the measured and calculated values compare?.
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2. Is the voltage across a resistor directly or indirectly proportional to the current
through it?.
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3. In step 6 the voltage was increase from 10 to 20 V. The resistance remained
unchanged. Did the results of your measurements and calculations for this step
confirm Ohm’s law? Explain.
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4. In step 7, two resistors were used. Did your calculation of RT equal the sum of the two
resistors?
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5. Explain Ohm’s law in your own words.
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6. A 9V battery is used to supply voltage to a resistive circuit. Calculate the resistance
value if the current flows through the resistor is 5mA
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