1. Topic – Photo Electric Effect
Subject Code – BSPH101
Collage – Mallabhum Institute of Technology
Student Name – Subhadeep Patra
Department – Computer Science Engineering
Roll No. – 33
2. Contents
Introduction to Photo Electric
Effect
Photon
Energy of Photon
Properties of Photon
Construction and Working
Photoelectric effect-working
Mathematical Description
Conclusion
3. Introduction
What is Photo Electric Effect ?
During his experiment on EM waves, Hertz
noticed that sparks occurred more readily in
the gap of his transmitter when ultraviolet
light was
Directed on one of the light balls. He didn't
follow up this observation, but others did.
They soon discovered that the cause was
electrons emitted when the frequency of light
was sufficient high.
When a beam of light of sufficiently high
frequency onto a clean metal surface then the
light will cause electrons to leave the surface.
4. Definition:
The phenomenon of emission of electrons by the
metals when they are exposed to light of suitable
frequency is called as the photo electric effect and
emitted electrons is called as photoelectrons.
Photon Absorption: Light, made of photons, hits a
material, and electrons in the material absorb individual
photons.
Emission of Electrons: If absorbed photon energy is
sufficient, electrons overcome the material's binding
energy and are ejected, emitting photoelectrons.
Threshold Frequency: Electrons are emitted only if light
exceeds a specific frequency (threshold), related to the
minimum energy needed to free an electron.
Instantaneous Emission: Photoelectrons are emitted
instantly when the material is exposed to light of the
right frequency, with no delay. The emitted electrons'
number is proportional to light intensity.
Photo Electric Effect
5. Photon
In 1905, Einstein proposed the idea that light is
composed of discrete energy packets called photons.
This concept challenged the classical view of
continuous light waves.
Einstein's theory suggested that light energy is
emitted not continuously but in distinct amounts
known as quanta or quantum of energy.
Each photon carries a specific amount of energy,
marking a departure from the smooth and
continuous energy transfer associated with classical
wave theory.
The quantum nature of light explained phenomena
such as the photoelectric effect.
Einstein's work laid the foundation for quantum
mechanics, transforming our understanding of the
dual nature of light.
6. Energy of Photon
According to Einstein, each photon
of a light wave of frequency has the
energy E is given by,
E = h ⋅ ν (1)
Where,
E = energy of photon (joule)
h = planks constant - 6.626 x 10 - 34 J.s
v = frequency of photon(Hz)
7. Properties of Photon
A photon does not have any mass.
A photon does not have any charge
and are not deflected in electric field
or magnetic field.
All the quantum numbers are zero
for a photon.
n empty space, the photon moves at
speed of light.
In the interaction of radiation with
matter, radiation behaves as if it is
made up of particles called photons.
8. Construction and Working
The Hertz experimental set up used
for studying the photoelectric effect
is shown in above fig.
The set up consist of an evacuated
glass tube that has a photosensitive
metal plate C and another metal plate
A as shown. A monochromatic light
source emerging from the source S of
sufficiently short wavelength enters
the glass window W and fall on
photosensitive plate C, is called
emitter.
9. Photoelectric effect-working
when a beam of light fall on photosensitive metal plate c
which is called emitter.
The plate c emits photoelectrons due to photoelectric
effect. The photo electrons emitted by plate will be
attracted towards the positive plate.
these electron flows in the eternal circuit to cause an
electric current in the circuit.
Such a current is known as the photoelectric current and
measured by the micrometer connected in the circuits
10. Mathematical Description
Maximum K.E of ejected electron is given by,
Kmax = hν – φ
Where,
H = planks constant
V = frequency of incident photon
φ = work functionWhere
Vo= frequency for metal
So,
Kmax = h (v - vo )
K.E is +ve so we must have v > vo foe the photoelectric effect
to occur.
11. Conclusion
Scientific Foundations Unveiled:
The Photoelectric Effect emerges as a foundational revelation in the realm
of quantum physics, unraveling intricate aspects of light-matter
interactions through quantized energy states.
Historical Significance Illuminated:
Our exploration delved into the historical context, unveiling the roots and
evolutionary journey of the Photoelectric Effect, providing valuable insights
into its significance across scientific milestones.
Crucial Role in Quantum Understanding:
Emphasizing its pivotal role, the Photoelectric Effect serves as a linchpin in
comprehending the quantum nature of light, ushering in a new era of
scientific understanding and challenging classical paradigms.
Thank You:
Thank you for joining this exploration into the captivating world of
polarization.
