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Laboratory Report: The Photoelectric Effect
Name: _________________________________
Introduction
The photoelectric effect is a phenomenon where electrons are ejected from a metal surface when
it is exposed to light of a certain frequency. This experiment aims to investigate the work
function of various metals by utilizing a simulation. The work function is the minimum energy
required to eject an electron from the surface of a metal. This lab activity employs the PhET
Interactive Simulations to conduct the experiment and gather data.
Objectives
1. Discuss the photoelectric effect.
2. Solve problems involving the photoelectric effect.
3. Devise experiments and write satisfactory laboratory reports.
Materials and Methods
Materials:
Computer with internet access
PhET Interactive Simulations
Procedure:
1. Visit the PhET Interactive Simulations website and run the "Photoelectric Effect"
simulation.
2. Set the battery voltage to 0V.
3. Turn the light intensity to 100%.
4. Select the metal (sodium) from the upper right-hand box.
5. Adjust the wavelength until electrons are ejected at the lowest possible speed.
6. Record the wavelength.
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7. Repeat steps 4-6 for other metals (zinc, copper, platinum, calcium, and a mystery metal).
Data and Observations
Recorded Wavelengths:
Metal Wavelength
Sodium 539nm
Zinc 288
Copper 263
Platinum 196
Calcium 427
W 335
Calculations
Constants:
Speed of light, c = 2.998 × 10^17 nm/s
Planck's constant, h = 6.626 × 10^-34 J·s
1 electron volt = 1.60217646 × 10^-19 joules
Formulas:
1. c = λν
2. hν = W (since Ek = 0)
Example Calculation for Sodium:
Wavelength (λ) = 539 nm
Frequency (ν) = c/λ = (2.998 × 10^17) / 539 = 5.5612 × 10^14 s^-1
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Energy (hν) = h × ν = 6.626 × 10^-34 × 5.5612 × 10^14 = 3.682 × 10^-19 J
Work function (W) in eV = (3.682 × 10^-19) / (1.60217646 × 10^-19) = 2.30 eV
Calculated Work Functions:
Sodium: 2.30 eV
Zinc: 4.29 eV
Copper: 4.73 eV
Platinum: 6.33 eV
Calcium: 2.90 eV
Mystery Metal: 3.70 eV
Graph
Sodium Zinc Copper Platinum Calcium Mystery
Metal
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1
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3
4
5
6
7
ev
The bar graph above shows the work functions of various metals as determined from the
photoelectric effect experiment. Platinum has the highest work function at 6.33 eV, while
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Sodium has the lowest at 2.30 eV. The mystery metal, identified as Magnesium, has a work
function of 3.70 eV, fitting between Zinc and Calcium in the series.
Results
The calculated work functions were compared with known values to identify the mystery metal.
The mystery metal was determined to be Magnesium, which has a work function close to the
calculated 3.70 eV.
Conclusion
The experiment successfully demonstrated the photoelectric effect and allowed for the
determination of the work functions of various metals. The simulation provided an interactive
and effective means to understand the quantum nature of light and the energy required to eject
electrons from different metal surfaces. By calculating the work functions and comparing them
with known values, we could identify the mystery metal, thus fulfilling the objectives of the lab
activity.
References
