Day 14: Current Voltage and Resistance

  We have a wire, bulb and battery. We need to make the bulb light.

  There are three arrangements that the bulb will light and not light.

 
  There are the explainations that why these two arrangement can not light.

  Now we have two batteries so we can make the bulb brighter.

  Professor use a rubber bar rubbing it to animal skin and put the bar on the ball. Then the two pieces of sheetmetal separate.

  We predict nothing will happen when battery on the ball.

  Bulb can light because there is a circle between the battery and the bulb and the charges can equilibrium.

  There are two things relate to waterfall.

  There is an exercise we did to found power by using V and I.

  We used the equipment to measure the current and we got 124 mA. If we reverse, we found it goes opposite direction.

  We predict the model c is correct, but experiment showed the direction of the current will be same in both wires.

  We found out the things that will influence current.

  There are the relationship between current and voltage by using Ohm's law.

  There are the current and voltage graphs we found by using Logger Pro.

  There are two graphs: V vs. C and C vs. V.

  We found the unit for resistance.

  We used the equipment in the first picture and found the longer length has larger resisitivity.

  In this picture, we found the larger diameter or area will get smaller resistivity.

Conclusion:
  At beginning of the class, we did a very interesting experiment to made a bulb light by using battery and wire. And we found different arrangements will make bulb light or not.Then we found the relationship between current, voltage and resistance by Joules Law. Then we started to learn Ohm's Law, we found the proportionality of current and voltage are related to resistors. Last, we found the unit for resistance, a very interesting Greek letter.