The Photoelectric Effect

The Photoelectric Effect

Introduction:

When charged particles are released from a metal which is under the electromagnetic radiation,such as light,x-rays etc.. A so called ‘photoelectric effect might occur. In our experiment, we decided to use an online simulation on the internet:

https://www.thephysicsaviary.com/Physics/Programs/Labs/PhotoelectricEffect/index.html\

Our hypothesis is that all four variables in this computer simulation (wavelength,brightness,voltage and the type of element) influence the numbers of the electron detected in a certain amount of time. In our experiment, we study the effect of the two variables on a given metal, Potassium

Experiment:

This is a screenshot of the online experimental simulation. The values of four variables that can be modified:

Wavelength(100nm-900nm): The blue ray in the diagram meaning the light sent .

Brightness(20-120 photons/min): The numbers of photons ejected per minute.

Voltage(0 to 5V): adding positive charge on the side of the metal board, attracting the negative electrons.

Metal board: changing the element type（copper，potassium, sodium…)

Method:

In order to do this, I set up two experiments. In the first one, the independent variable is wavelength. I estimate that as the wavelength increases, the velocity of the electrons ejected back to the detector decreases. We measure the electrons detected in thirty seconds when the brightness is always 60 photons per minute.

Data collection and graphs:

Wavelength(nm)

Trial 1

Trial 2

Average

390

26

21

23.5

420

27

26

26.5

450

30

24

27

480

33

29

31

510

30

19

24.5

540

0

0

0

In this graph, we cannot draw the conclusion that these data points have a trend. This does not suggest a correlation between the electrons detected in 30 seconds and the wavelength.We know that the stopping potential is controlled as 0V and brightness is 60 photons per minute. This shows that the data we collected in this case, is random. But starting

...