Activity 3. Resistivity

Report 3 resistivity

Aim:

 To find out the effect of these variables (wire length, wire area and wire density) to the resistance of a wire.

Hypothesis:

The formula for resistance in wire is:

Resistance = (wire density) x (wire length)

                                          (wire area)

So I think; as wire density and wire length increases, resistance will increase too. The only different one is wire area, as the area widen the resistance will decrease.

Background Information:

We’ve learnt a bit about resistance, but nothing about resistance in a wire. Resistance equals to voltage/current while resistance in a wire has a different formula. The formula has been stated in the hypothesis. The unit of resistance is ohm or also known as omega.

Manipulative variable:

Independent:                          

The value of variable used (e.g: 0.50 ohmcm, 10 cm)

Controlled:

Value of resistance

Dependent:        

The effect of each variable to the resistance in a wire    

Material/Apparatus:

Resistance in wire simulation (PHeT)

Procedure:

1.)  First, you set the simulation. Leave resistance alone. (We will alter the other variables available)

2.)  First to increase the wire length and see what happens to the value of resistance. Record the data.

3.)  Undo and do the same thing with the other two variables (wire density and wire area)

4.)  Record the data of both of them.

Data:

Resistance (ohm)	Wire density (ohmcm)	Wire length (cm)	Wire area (cm square)
0,67	0,50	10	7,50
1,33	0,50	20	7,50
0,33	0,50	10	15
1,33	1	10	7,50

Analysis: (Table analysis)

            In the first row, that is the first constant. We didn’t alter anything yet; the values are perfectly the same as the value on the net. In the second row we tried to change the value of wire length to 20 cm and the result we got was the increase of the value of resistance to 1,33 ohm. This proved that as the wire length increases, the resistance would increase too. They’re directly proportional. In the third row we altered the value of wire area to 15 cm square and the result was the decrease of the value of resistance, this proved that resistance and wire area is indirectly proportional. In the last row we altered the value of wire density into 1 ohmcm and the result was an increase in the value of resistance. This proved that resistance is directly proportional to wire density.

Conclusion:

We proved our hypothesis right, both wire density and wire length are directly proportional to resistance in a wire, while wire are is indirectly proportional to the resistance in a wire. We have proven this through our data.

Evaluation:

Maybe we slack a lot, next we need to use the time given by our teacher wisely so that we can finish our work on time and submit it on time too.