Aspects of Photoelectric Effect with Different Metals and Lights
Hypothesis:
signs of photoelectric effect would be present as photoelectric effect
is commonly intrinsic for metals
Variables:
independent: type of metal, type of light, light intensity, distance
between light source and metal
dependent: current magnitude
controlled: temperature, pressure
Apparatus and materials:
zinc plates, copper plates, ultraviolet light, light bulbs, power
source, ammeter, voltmeter, coulombmeter, sandpaper, wires, crocodile
clips, caesium-antimony photocathode
Method for the control of variables:
the temperature and pressure are kept constant throughout the
experiment; the experiment is conducted within a reasonably short
period of time
Method for the collection of sufficient relevant data:
This is the experimental setup:
Photons of UV light should knock electrons off from the plate 2. Plate
2 then becomes positively charged. Electrons reach plate 1 and it
becomes negatively charged. Electric potential is thus established in
the circuit between plates 1 and 2 which induces the flow of electrons
counter clockwise from plate 1 to plate 2, which should be registered
by the ammeter. After the electrons would move from plate 1 to plate
2, both plates would be neutral again, which means the absence of
electric potential, and thus current. Constant stream of photons
should knock more electrons off the plate 2, which would re-establish
the potential, and thus provide a continuous current.
The experiment is repeated using different metals and light sources,
including variations of light intensity and wavelength, and different
distances between a light source and a metal surface.
Data Collection, Processing and Presentation:
The wavelength of UV light varies from 200 to 400 nm approximately.
The UV light from the UV lamp used was around 400 nm in wavelength.
Thus, wavelength of photoelectric threshold of the metal should be
longer than 400 nm.
However the metals used, zinc and copper, have photoelectric
thresholds of 290 nm and 270 nm respectively. Thus the photoelectric
effect did not occur during the experiment.
Conclusion and Evaluation:
In order to make the decision, this report measures the following qualitative and quantitative areas:
How would you summarize your results and analysis? What questions remain unanswered? What questions were raised by your results and analysis?
2. Your conclusion paragraph should be more detailed. Restate in just a few sentences the points that you made in your paper and what conclusions you have drawn from those points.
Reflecting on your delivery and relating to further reading and research, write a personal analysis which considers the following:
B. FINAL THOUGHTS (What should the reader consider or remember? How should reader act on this issue?
The Effect of Intensity on the Power of Solar Cells This experiment involves changing the intensity of light falling on different cells and measuring their power outputs. Higher intensity of light means that there are more photons hitting the surface of the cell per unit area per second. The more hit the cell, the more rapidly the electrons move across the p-n junction, so the larger the emf produced. If the rate of movement of electrons is inhibited, then the greater the rate of supply of photons (intensity), the more will not successfully excite an electron, so the lower the efficiency of the cell.
Individual atoms can emit and absorb radiation only at particular wavelengths equal to the changes between the energy levels in the atom. The spectrum of a given atom therefore consists of a series of emission or absorption lines. Inner atomic electrons g... ... middle of paper ... ... a sensitive multielement inorganic analyses.
The findings are then summarised and accordingly stated with the help of standard methodologies which are then concluded providing with the various limitations and the recommendations.
Electroplating Experiment Aim To find the amount copper gains or loses on the electrodes using different amounts of current each time during electrolysis. How the changing of current affects the electroplating of copper. Introduction Electroplating is generally carried out in order to improve the appearance or corrosion resistance of the surface of a metal by electrodepositing a thin layer of metal ion on it. The metal substrate to be coated is made by the cathode in an electrolytic cell. The cell used in electroplating contains an electrolyte which is usually an aqueous solution containing a reasonably high concentration of an ion of the metal which is to be electroplated on the surface.
The photovoltaic effect, electricity can be created directly from sunlight. Some semi-conductor materials that are exposed to sunlight can create electron-hole pairs, which can be collected to produce electricity. This occurs when photons have energy above a certain threshold. These photons have shorter wavelengths. In silicon, the threshold for electron-hole production is in the infrared region of the electromagnetic spectrum.
Davisson and Germer found that by varying the applied voltage to the electron gun, the maximum intensity of electrons diffracted by the atomic surface was found at different angles. The highest intensity was found to be at an angle θ = 50° with a voltage of 54 V, giving the electrons a kinetic energy of 54 eV.
Solar Cell Experiment Aim: To see how individual factors affect the output of a solar cell. Factors affecting the output of a solar cell: This experiment is going to be performed in the confines of a school laboratory, and so the complexity and cost of the experiment(s) should reflect this. However, to see how different factors affect the solar cell output, I will need to perform at least two experiments. The question is, which ones? · Distance from the light source will affect the solar cell output, because intensity of light on the solar cell will decrease, the further away from the light the cell is.