Ohm's+Law+-+Swathi,+Michael,+Nick

=**Tit**le of Lab: Ohm's Law=

Research Question:
What is the relationship between the voltage across an Ohmic device and the current flowing through the device?

Research:
__Ohm's Law__ - electric current is directly proportional to voltage and inversely proportional to resistance We can then find the equation: V = IR From this, we can see that V/I equals a constant value R. In order to test both voltage and current of an Ohmic device, an experiment was conducted according to the following set-up: With regard to the resistor, the following code has been created:

Hypothesis:
The voltage across an Ohmic device has a direct linear relationship with the current flowing through the device.

**Materials:**
ammeter, voltmeter (with attached "probes"), D.C. power source, resistor, alligator clip wires

**Procedure:**
1) Attach one end of the resistor to the ammeter. 2) Connect one wire directly from the power source to the ammeter and connect another wire from the power source to the other end of the resistor. Be sure to use direct current. 4) "Calibrate" your voltmeter by touching the two probes to each other and making sure the reading on the voltmeter is zero. 5) Touch the ends of the two probes to both ends of the resistor and write down the voltage. Do this for various currents from 0 amps to 0.20 amps.


 * Data: **


 * Data Analysis: **

[[image:graph4.JPG width="409"]]
The equation of our line is y = 68.8x The y-intercept is 0 volts, which is the only sure point on the graph with no error because with a value of 0 Amps of current, 0 Coulombs are being transferred through the wire, leaving a potential difference (or voltage) of 0 volts. Our slope represents the resistance of the system (resistance=voltage/current), experimentally tested as 68.8 Ohms. Our Blue-Red-Black-Gold banned resistor, when analyzed using the resistor code shown above, showed the actual resistance was 62 Ohms with a tolerance of 5%. This leaves us in a range of percent error between 5.74% and 16.9%. This range of percent error could have been caused by some of the following reasons: movement when holding the voltmeter probes, negligence to "re-calibrate" the voltmeter before every trial, lack of precision in the ammeter, slight resistance in the wire itself, and also a slightly damaged resistor (due to burning).

**Conclusion:**
Our hypothesis was justified by both our experiment and Ohm's law, for there is a clear direct linear relationship between the voltage and current in an Ohmic device, and the slope of this relationship (the resistance) is very close to the actual resistance of the resistor. Though Ohm's law is widely accepted and well-known in physics, our experiment was not perfect. In order to achieve greater accuracy in another trial, we could use a more precise ammeter, a brand new wire, a more sophisticated voltmeter (rather than a multimeter), or a different, undamaged resistor.