PASCO SE-6609 User manual

Instruction Manual 012-13943B
Photoelectric Effect Apparatus
Model No. SE-6609
Equipment List
Included Equipment
1. Mercury Light Source Enclosure
2. Track, 60 cm
3. Photodiode Enclosure
4. Mercury Light Source Power Supply
5. DC Current Amplifier
6. Tunable DC (Constant Voltage) Power Supply
Optical Filters, Apertures, and Caps
7. Filter Wheel (365, 405, 436, 546, 577 nm)
8. Aperture Dial (2 mm, 4 mm, 8 mm diameter)
Photodiode Enclosure Cap (not shown)
Mercury Light Source Enclosure Cap (not shown)
1.
2.
3.
4. 5.
6.
10.
11.
12.
7.
8.
10.
3.
11.
12.

Photoelectric Effect Apparatus SE-6609
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*See the PASCO web site at www.pasco.com for more information.
Limited Warranty and Limitation of Liability
This Brolight product will be free from defects in material and workmanship for one year from the date of purchase. This
warranty does not cover fuses, or damage from accident, neglect, misuse, alteration, contamination, or abnormal conditions of
operation or handling. Resellers are not authorized to extend any other warranty on Brolight's behalf. To obtain service during
the warranty period, return the unit to point of purchase with a description of the problem.
THIS WARRANTY IS YOUR ONLY REMEDY. NO OTHER WARRANTIES, SUCH AS FITNESS FOR A PARTICULAR
PURPOSE, ARE EXPRESSED OR IMPLIED. BROLIGHT IS NOT LIABLE FOR ANY SPECIAL, INDIRECT,
INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSSES, ARISING FROM ANY CAUSE OR THEORY. Since
some states or countries do not allow the exclusion or limitation of an implied warranty or of incidental or consequential
damages, this limitation of liability may not apply to you.
Safety Information
Warning: To avoid possible electric shock or personal injury, follow these guidelines:
• Do not clean the equipments with a wet rag.
• Before use, verify that the apparatus is not damaged.
• Do not defeat power cord safety ground feature.
• Plug in to a grounded (earth) outlet.
• Do not use product in any manner not specified by the manufacturer.
• Do not install substitute parts or perform any unauthorized modification to the product.
• Line and Current Protection Fuses: For continued protection against fire, replace the line fuse and the current-protection fuse only
with fuses of the specified type and rating.
• Main Power and Test Input Disconnect: Unplug instrument from wall outlet, remove power cord, and remove all probes from all
terminals before servicing. Only qualified, service-trained personnel should remove the cover from the instrument.
Cables and Cords
9. Power Cord (3) (110 V version shown)
10. BNC Connecting Cable, Photodiode Enclosure
11. Connecting Cable, Red
12. Connecting Cable, Black
13. Interface Cable (3) UI-5219
Recommended Equipment* Model
PASCO 850 Universal Interface UI-5000
PASCO Capstone Software UI-5400
Replacement Items* Model
Replacement Mercury Lamp SE-6597
Replacement Photodiode Tube SE-6612
9. 10.
11.
12.
13.

Safety Information 012-13943B Photoelectric Effect Apparatus
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• Do not use the equipment if it is damaged. Before you use the equipment, inspect the case. Pay particular attention to the
insulation surrounding the connectors.
• Do not use the equipment if it operates abnormally. Protection may be impaired. When in doubt, have the equipment serviced.
• Do not operate the equipment where explosive gas, vapor, or dust is present. Don't use it under wet condition.
• Do not apply more than the rated voltage, as marked on the apparatus, between terminals or between any terminal and earth
ground.
• When servicing the equipment, use only specified replacement parts.
• Use caution when working with voltage above 30 V AC RMS, 42 V peak, or 60 V DC. Such voltages pose a shock hazard.
• To avoid electric shock, do not touch any naked conductor with hand or skin.
• Adhere to local and national safety codes. Individual protective equipment must be used to prevent shock and arc blast injury
where hazardous live conductors are exposed.
• Remaining endangerment: When an input terminal is connected to dangerous live potential it is to be noted that this potential can
occur at all other terminals!
Electrical Symbols
Alternating Current
Direct Current
Caution, risk of danger, refer to the operating manual
before use.
Caution, possibility of electric shock
Earth (ground) Terminal
Protective Conductor Terminal
Chassis Ground
Conforms to European Union directives.
WEEE, waste electric and electronic equipment
Fuse
On (Power)
Off (Power)
In position of a bi-stable push control
Out position of a bi-stable push control

Photoelectric Effect Apparatus SE-6609
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Introduction
The photoelectric effect is the emission of electrons from the surface of a metal when electromagnetic radiation (such as visible
or ultraviolet light) of the right frequency shines on the metal. At the time of its discovery, the classical wave model for light
predicted that the energy of the emitted electrons would increase as the intensity (brightness) of the light increased.
Instead it was discovered that the energy of the emitted electrons was directly proportional to the frequency of the incident
light, and that no electrons would be emitted if the light source was not above a certain threshold frequency. Lower energy
electrons were emitted when light with relatively low frequency was incident on the metal, and higher energy electrons were
emitted when light with relatively high frequency was incident on the metal.
About the Apparatus
The SE-6609 Photoelectric Effect Apparatus consists of a mercury light source enclosure, a track, a tunable direct current (DC)
constant voltage power supply, a DC current amplifier, a power supply for the mercury light source, miscellaneous cords and
cables, a photodiode tube enclosure that has optical filters with five different frequencies and an aperture disk with three
different diameters, and protective caps for the photodiode enclosure and the mercury light source enclosure. The photodiode
enclosure and the mercury light source enclosure mount on the included track.
The apparatus has several important features:
• The current amplifier has high sensitivity and is very stable in order to improve the accuracy of the measurement.
• The photodiode tube has low levels of dark current and anode reverse current.
• The optical filters are of high quality in order to avoid an error due to interference between different spectral lines.
When connected to a PASCO Interface using PASCO Data Acquisition Software (such as PASCO Capstone), the current and
voltage can be measured, recorded, displayed and analyzed.
Background Information
Many people contributed to the discovery and explanation of the photoelectric effect. In 1865 James Clerk Maxwell predicted
the existence of electromagnetic waves and concluded that light itself was just such a wave. Experimentalists attempted to
generate and detect electromagnetic radiation and the first clearly successful attempt was made in 1886 by Heinrich Hertz. In
the midst of his experimentation, he discovered that the spark produced by an electromagnetic receiver was more vigorous if it
was exposed to ultraviolet light. In 1888 Wilhelm Hallwachs demonstrated that a negatively charged gold leaf electroscope
would discharge more rapidly than normal if a clean zinc disk connected to the electroscope was exposed to ultraviolet light. In
1899, J.J. Thomson determined that the ultraviolet light caused electrons to be emitted from the metal.
In 1902, Phillip Lenard, an assistant to Heinrich Hertz, used a high intensity carbon arc light to illuminate an emitter plate.
Using a collector plate and a sensitive ammeter, he was able to measure the small current produced when the emitter plate was
exposed to light. In order to measure the energy of the emitted electrons, Lenard charged the collector plate negatively so that
the electrons from the emitter plate would be repelled. He found that there was a minimum “stopping” potential that kept all
electrons from reaching the collector. He was surprised to discover that the “stopping” potential, V, - and therefore the energy
of the emitted electrons - did not depend on the intensity of the light. He found that the maximum energy of the emitted
electrons did depend on the color, or frequency, of the light.
In 1901 Max Planck published his theory of radiation. In it he stated that an oscillator, or any similar physical system, has a
discrete set of possible energy values or levels; energies between these values never occur. Planck went on to state that the
emission and absorption of radiation is associated with transitions or jumps between two energy levels. The energy lost or
gained by the oscillator is emitted or absorbed as a quantum of radiant energy, the magnitude of which is expressed by the
equation: E = h
 where Eequals the radiant energy,  is the frequency of the radiation, and his a fundamental constant of
nature. (The constant, h, became known as Planck's constant.)

Principle of the Experiment 012-13943B Photoelectric Effect Apparatus
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In 1905 Albert Einstein gave a simple explanation of Lenard’s discoveries using Planck’s theory.
The new ‘quantum’-based model predicted that higher frequency light would produce higher
energy emitted electrons (photoelectrons), independent of intensity, while increased intensity
would only increase the number of electrons emitted (or photoelectric current). Einstein assumed
that the light shining on the emitter material could be thought of as ‘quanta’ of energy (called
photons) with the amount of energy equal to h
 with  as the frequency. In the photoelectric
effect, one ‘quantum’ of energy is absorbed by one electron. If the electron is below the surface of
the emitter material, some of the absorbed energy is lost as the electron moves towards the
surface. This is usually called the ‘work function’ (Wo). If the ‘quantum’ is more than the ‘work
function’, then the electron is emitted with a certain amount of kinetic energy. Einstein applied
Planck's theory and explained the photoelectric effect in terms of the quantum model using his
famous equation for which he received the Nobel prize in 1921:
where KEmax is the maximum kinetic energy of the emitted photoelectron. In terms of kinetic energy,
If the collector plate is charged negatively to the ‘stopping’ potential so that electrons from
the emitter don’t reach the collector and the photocurrent is zero, the highest kinetic energy
electrons will have energy eV where eis the charge on the electron and Vis the ‘stopping’
potential.
Einstein’s theory predicts that if the frequency of the incident light is varied, and the
‘stopping’ potential, V, is plotted as a function of frequency, the slope of the line is h/e (see
Figure 1).
Principle of the Experiment
When incident light shines on the cathode (K), photoelectrons can be emitted and
transferred to the anode (A). This constitutes a photocurrent. By changing the voltage
between the anode and cathode, and measuring the photocurrent, you can determine the
characteristic current-voltage curves of the photoelectric tube.
The basic facts of the photoelectric effect experiments are as follows:
• For a given frequency (color) of light, if the voltage between the cathode and anode, VAK, is
equal to the stopping potential, V, the photocurrent is zero.
• When the voltage between the cathode and anode is greater than the stopping voltage, the
photocurrent will increase quickly and eventually reach saturation. The saturated current is
proportional to the intensity of the incident light. See Figure 2.
• Light of different frequencies (colors) have different stopping potentials. See Figure 3
• The slope of a plot of stopping potential
versus frequency is the value of the ratio,
h/e. See Figure 1.
• The photoelectric effect is almost
instantaneous. Once the light shines on the
cathode, photoelectrons will be emitted in
less than a nanosecond.
Albert Einstein
Eh  KEmax W0 +==
KEmax h  W0 –=
Frequency, 
V
Fig. 1: Stopping Potential, V,
versus Frequency
Anode
Cathode
Ammeter
Voltmeter
VAK
eV h  W0 –=
Vh
e
---

W0
e
--------
–=
Intensity 2
Intensity 1
VAK
I
Stopping
Potential
VAK
IFrequency 2
Frequency 1
Vstop 2
Vstop 1
Fig. 2: Current vs. Intensity Fig. 3: Current vs. Frequency