Experiment to Verify Ohm’s LawRolla Tyas Amalia

Grade 11

“For a conductor at constant temperature, the current in the conductor is proportional to the potential difference across it.”

Introduction

Ohm’s law is used in electrical engineering to calculate the relationships between

current, voltage and resistance. The calculations are required to design a safe

circuit. Ohm’s law is apply in our every-day life in electrical things that we use,

such as light bulbs, electric stoves, and others. Ohm’s law was discovered by a

scientist named Georg Simon Ohm. It published in his paper titled The Galvanic

Circuit Investigated Mathematically in 1827. Ohm’s principal discovery was that

the amount of electric current through a metal conductor in a circuit is directly

proportional to the voltage across it, for any given temperature. Ohm expressed

his discovery in the form of a simple equation, describing how voltage, current,

and resistance related to each other: V = I R

Hypothesis

The experiment setup consists of a simple circuit with a variable resistance and

simple power source, which are 3 batteries (1.5 Volt each). The diagram beside

shows the single circuit that we will use for this experiment:

We could choose a Voltage range and then vary

the value of the resistance over the range. As

expected from Ohm’s law, it will be seen the

voltage range and value of the resistance

chosen will be linear and the value of

resistance will be perpendicular to the current.

Experiment

Apparatus:

1. 4 varied value of resistors

2. Power supply

3. Connecting wires

4. Multimeter

Variables:

Independent: Resistance

Dependent: Current

Controlled: Electromotive force

Procedures:

1. Set up the apparatus to be the circuit as shown in diagram of hypothesis.

2. Set the value of electromotive force into 3 V.

3. Put the 12-ohm resistor and see the value of current in the Multimeter.

4. Change the 12-ohm resistor with 82 and 470-ohm resistor variedly and

repeat step 3.

5. Change the value of electromotive force into 6 V.

6. Repeat steps 3 and 4 (use 56-ohm resistor instead of 12-ohm resistor,

because the value of 12-ohm resistor is too small for 6V of electromotive

force).

7. Record the data in this table:

Analysis

Experiment In Calculation

Current Resistance Voltage V = IR

0.215 A 12 Ohm 3 V 2.58 V

0.037 A 82 Ohm 3 V 3.03 V

0.007 A 470 Ohm 3 V 3.29 V

0.105 A 56 Ohm 6 V 5.88 V

0.073 A 82 Ohm 6 V 5.98 V

0.013 A 470 Ohm 6 V 6.11 V

From this experiment, we can see that the values of voltages depend on how big

are the values of resistors. The bigger the values of resistors, the bigger the

values of electromotive force will be resulted. This shows that the voltage range

and resistor value is linear to each other, while perpendicular with the value of

current. For more clear details, see the table of the experiment data above.

Conclusion

The value voltage range in a circuit will be linear with the value of resistor

chosen, and perpendicular with the value of current resulted.