day 3

1. Cooking Hot Dog.
In the first, Professor Mason prepares a hot dog. And he connect the hot dog with voltage 120 V 
before the experiment, we guess nothing will happen; however the hot dog is going to slowly cooded.

b.) Then, we have three parallel, and two perpendicular LED.
Answer is B.

experiment set up: 

When the hot dog is connected with a voltage 120V, we find that the first and last paralleled LED light is lighting clearly, and other paralleled light up too, Other 2 are stay at the dark.

After looking the LED light up, we find that the hot dog is smoking

Result : When the hot dog is connected with a 120 V, we can know it has current goes though it, so that the LED light up, and hot dog goes to smoke. In the lab, there are only paralleled LED light up because there have different electric potential energy on the two side. But when the LED light is horizontally, there are not light because their two sides are same.

2. Dusk to Dawn Light

The purpose of the lab is going to build a circuit that is light sensitive by connecting a bipolar junction transistor to be a current controller, When we obstruct the light, the different voltage will be calculated. When the it is light, the resistance is 20k, and 1.67V. When it is not light, the resistance is 5k and 3.33V.

  Experience set up:

 When it gets dark(I use my close to obstruct light), the LED light starts to light up. When I move the close back, the LED light gets dark.

 When the LED light do not light up, measure the voltage across the resistor is 1.82V, Its % difference is -8.98.

  When the LED light do light up, measure the voltage of it across the resistor is 2.60V. The % difference is 21.9.

The both big % different is caused by room light, and my close can not apply a grade dark room.