Activity 4: Ohm's Law

Wire Resistance and Ohm’S Law  

Aim:

To observe the relationship between potential (volts), resistance (ohms) and current (amps)

Hypothesis:

As voltage increases, the current will also increases while the resistance will decrease.

Theory Background:  

In a circuit, there three main things or components that truly affect the electricity flows that happen in a circuit. Those three components are voltage (V), current (I), and resistance (Ω).  An electrical circuit is a complete course of conductors which the current can travel through it.  A voltage is the potential energy that makes the electrical current flow in the circuit by pushing the electrons. If current is a flow of electrical charge in the circuits. There usually two charges, that is positive and negative. And last is resistance, a resistance is anything that slows or stops movement or keep movement from happening.

Manipulative Variable:  

• Independent: Potential (volts) and Resistance (ohms)  
• Control: Current (amps)
• Dependent: Changes of potential (volts) and resistance (ohms) slider and observe the current (amps)

Materials:

• Simulation Program (Resistance in a wire and Ohm’s Law)
• Laptop
• Table Data

Procedure:

1. Construct the circuit based on the instruction using the simulation program
2. Move the potential (volts) and resistance (ohms) sliders and observe the current (amps)

Data:  

Data 1:

• As voltage increases, current increase
• As resistance increases, current decrease

Data 2:

                  V                              =                     I                            *                      R

8.0 V	0.01 A	800
2.0 V	0.44 A	450
2.5 V	0.058 A	430
6.9 V	0.069 A	100
6.4 V	0.021 A	300

Data 3: 

As wire length (cm) increases, the resistance (Ω) increase
As wire area (cm2) increases, the resistance (Ω decrease
As wire density (Ωcm), the resistance (Ω) increase

Analysis

1. Incandescent light bulbs have a very thin filament that glows when hot. the filament have a very high resistance.
2. The 12V battery operate in your car 25 amp car stereo, while the resistance of this stereo system is 0.48.
3. A “2D” Maglite flashlight runs on 3.0 V that means the current of the light bulb if the resistance is 15 is 0.2 A
4. The volts that is need to charge an iPOD that uses 0.85 Amps and 35 Ω is 29.75 V.
5. We need to but a long extension cord to power a stereo at our spring break BBQ. We need 200 feet and 50 ft cord that will work. However, this is not a good idea because if we do it, it means that the resistances will 4 times as the volts. That lead the voltage to drop will be 4.

Conclusion:

It is seems that our hypothesis is likely correct because during our experiment, its shows by the sliders that reaction of the voltage and current is increase. While the resistance, shows an opposite reaction and decreases.

Resources:
http://www.qrg.northwestern.edu/projects/vss/docs%20/propulsion/2-what-is-resistance.html
http://en.wikipedia.org/wiki/Electric_current
http://science.howstuffworks.com/what-is-voltage.htm