mod 1 and 4 Flashcards
Which display type is more energy-efficient and commonly used in portable devices?
LCD displays, as they consume less power and are used in smartphones, laptops, and tablets.
What determines the color of the light emitted by an LED?
The color is determined by the semiconductor’s bandgap energy—the energy difference between the conduction and valence bands—dictating the wavelength of the emitted photon.
What role does bandgap energy play in an LED?
The bandgap energy determines the energy (and hence the color) of the emitted light. A larger bandgap produces high-energy (blue) light, while a smaller bandgap produces lower-energy (red) light.
What is radiative recombination in semiconductors?
It is the process where an electron from the conduction band recombines with a hole in the valence band, releasing energy as a photon.
What is the significance of the refresh rate in an LED display?
A high refresh rate ensures smooth motion and image stability, preventing flickering and maintaining clear visuals even in dynamic video content.
What is the basic structure of an LED?
An LED is built around a p-n junction formed by doping a semiconductor material to create p-type (hole-rich) and n-type (electron-rich) regions.
Why do we normalize a wave function in quantum mechanics?
Normalization ensures that the total probability of finding a particle in the allowed region is 1, meaning:
[
\int_{0}^{a} |\psi (x)|^{2} \,dx = 1
]
Which display type has better contrast and deeper blacks?
Plasma displays, because they emit their own light and don’t rely on a backlight.
How does the uncertainty principle explain electron orbitals?
Classical orbits violate the uncertainty principle.
Electrons exist in probability clouds (orbitals).
The Schrödinger equation describes electron position as a wavefunction.
How does non-radiative recombination affect photovoltaic devices?
It reduces the conversion efficiency by dissipating energy as heat instead of converting it into electrical energy.
Why is wave-particle duality important in quantum mechanics?
It explains the fundamental behavior of microscopic particles and has led to advancements in quantum technologies like quantum computing, electron microscopes, and semiconductor devices.
What is the difference between AMOLED and PMOLED?
PMOLED (Passive-Matrix OLED): Simple, used for small displays (e.g., fitness bands).
AMOLED (Active-Matrix OLED): Uses transistors for better control, used in phones and TVs.
What is gas discharge in plasma displays?
A process where electricity excites gases like xenon and neon, making them release ultraviolet (UV) light, which then lights up the phosphor coating to produce visible colors.
Define the photovoltaic effect.
The photovoltaic effect is the process of converting light energy into electrical energy through the excitation of electrons in a semiconductor.
What does Stefan-Boltzmann Law tell us about energy emission?
As the temperature of a black body increases, it emits more energy per unit area at a much higher rate (𝑇^4 dependence).
How do LED displays utilize backlighting?
In devices like LCDs, LEDs are used as backlights to provide uniform illumination, which enhances brightness, contrast, and energy efficiency.
Which display type consumes less power?
LCD – it is power efficient and uses less electricity than CRTs.
What does Planck’s law describe?
Planck’s law provides the mathematical expression for the spectral distribution of black body radiation. It defines how the intensity of radiation emitted varies with wavelength and temperature.
What is self-emissive technology?
Each pixel generates its own light, meaning no need for a backlight, resulting in better contrast and energy efficiency.
What function do driver circuits serve in an LED display?
Driver circuits control each LED’s on/off state and brightness by sending precise electrical signals, which are essential for forming the desired images.
What is refresh rate, and which display had better refresh rates in the past?
Refresh rate is how fast the screen updates images. CRTs had better refresh rates initially, but modern LCDs have improved significantly
What does external quantum efficiency (EQE) measure in an LED?
EQE measures how effectively the LED converts electrons into photons, accounting for losses due to internal recombination inefficiencies.
How do electrons create light in an FED?
Electrons emitted from the cold cathodes strike a phosphor-coated screen, making it glow.
Which display type is better for small, portable devices like laptops and phones?
Which display type is better for small, portable devices like laptops and phones?
What does the fill factor indicate in solar cell performance?
The fill factor is a parameter that reflects the quality of the current-voltage (I-V) characteristics and overall performance of the solar cell.
How does an LED emit light?
When forward-biased, electrons and holes are injected into the p-n junction, where electron-hole recombination occurs, releasing energy as light.
What is a Field Emission Display (FED)?
A flat-panel display that uses cold cathodes and field emission to excite phosphors and produce images.
How are Stefan-Boltzmann and Wien’s Laws related?
Wien’s Law tells us where most radiation is emitted (wavelength).
Stefan’s Law tells us how much energy is emitted (intensity).
Hotter objects emit more energy and shift to shorter wavelengths.
What is the energy-time uncertainty principle?
ΔEΔt≥ ℏ/4pi
If a state has a short lifetime (Δ𝑡
), its energy uncertainty (Δ𝐸) is large.
Explains unstable particle decays and quantum tunneling.
Where are Field Emission Displays used?
High-end TVs, monitors, and portable devices requiring fast response and low power.
How does Stefan’s Law apply to stars?
A hotter star (higher
T) emits significantly more radiation per unit area than a cooler one, making it brighter.
Why does observation affect the outcome of the double-slit experiment?
The act of measurement collapses the wave function, forcing the particle to behave like a particle instead of a wave.
Which display type is heavier and bulkier?
CRT – because of the large cathode ray tube inside.
Why is FED better than CRT?
Thinner & lighter
Lower power consumption
Faster response time
Better viewing angles & contrast
What is backlighting in LCD displays?
A light source (usually LED) behind the screen that provides illumination, as liquid crystals do not emit their own light.
How does the double-slit experiment demonstrate wave-particle duality?
When electrons or photons pass through two slits without observation, they form an interference pattern (wave-like behavior). When observed, they behave like particles, forming two distinct clusters.
What is the primary application of radiative recombination?
Radiative recombination is exploited in optoelectronic devices, including LEDs and semiconductor lasers, for efficient photon emission.
What is the basic structure of a PIN photodetector?
It has a p-doped region, an intrinsic (pure) region, and an n-doped region. The intrinsic region enhances light absorption and reduces recombination of charge carriers.
What is meant by the efficiency of a solar cell?
Efficiency measures how effectively a solar cell converts incident sunlight into electrical energy.
What are the two types of matrix structures in LCD displays?
Active matrix (uses transistors for better control and quality) and passive matrix (simpler, but slower and less precise).
What are cold cathodes in FED?
Tiny electron emitters that release electrons without heating, using a strong electric field instead.
Write the mathematical expression for Planck’s law.
𝐵(𝜆,𝑇)=2ℎ𝑐^(2)/𝜆^(5) *(1/𝑒^(ℎ𝑐/𝜆𝑘𝐵^(𝑇)) -1
where:
B(λ,T) is the spectral radiance,
h is Planck’s constant,
c is the speed of light,
λ is the wavelength,
B is Boltzmann’s constant, and
T is the temperature in Kelvin.
is Boltzmann’s constant, and
𝑇
T is the temperature in Kelvin.
What is de Broglie’s hypothesis?
De Broglie proposed that particles have an associated wavelength given by the equation:
𝜆=ℎ/𝑝
where λ is the wavelength, h is Planck’s constant, and p is the particle’s momentum.
What is the main technology behind LCD screens?
Liquid crystal technology, where liquid crystals control light passing through to create images.
What are common real-world applications of solar cells?
Solar cells are used in residential and commercial solar panels, remote power systems, satellites, and various renewable energy solutions.
What does OLED stand for?
Organic Light Emitting Diode
Which display type is thinner and lighter?
LCD – it has a space-saving design.
Why is OLED better than traditional LED/LCD screens?
No backlight needed (self-emissive)
✅ True blacks & better contrast
✅ More energy-efficient
✅ Flexible & ultra-thin
How do LCD displays create images?
Liquid crystals twist and control how much light from an LED backlight passes through, creating different colors and brightness levels.
What is the impact of Heisenberg’s Uncertainty Principle on quantum mechanics?
_Imposes a fundamental limit on measurement precision.
-Explains why electrons exist in orbitals, not fixed orbits.
-Supports wave-particle duality.
-Leads to probability-based quantum mechanics instead of deterministic classical mechanics.
How do sensitivity and noise performance differ between PIN and avalanche photodetectors?
PIN photodetectors offer lower sensitivity but generate less noise, making them ideal for high-speed, low-noise applications. APDs provide high sensitivity through internal gain but at the cost of increased noise due to the stochastic nature of the multiplication process.
What is doping and why is it important in LED design?
Doping involves adding impurities to a semiconductor to create either p-type or n-type regions, essential for forming the p-n junction and controlling the recombination process.
How does wave-particle duality relate to uncertainty?
Particles like electrons have a wave nature (de Broglie’s hypothesis).
A well-defined wavelength means precise momentum but uncertain position.
A localized wave means a precise position but uncertain momentum.
What does the term “intrinsic region” mean in photodetectors?
The intrinsic region is the undoped (pure) part of the detector where light absorption and initial charge carrier generation occur with minimal impurities, ensuring efficient operation.
What is the basic principle by which a solar cell converts sunlight into electricity?
It converts sunlight into electricity using the photovoltaic effect.
How does an OLED screen produce light?
OLED screens use organic materials that glow when electricity passes through them, a process called electroluminescence.
What does Stefan-Boltzmann Law state?
The total radiant energy emitted per unit area of a black body is directly proportional to the fourth power of its absolute temperature.
What role does bandgap energy play in radiative recombination?
The energy released as a photon during radiative recombination is approximately equal to the semiconductor’s bandgap energy.
How is the emission wavelength of an LED selected?
The emission wavelength is selected by choosing semiconductor materials with the appropriate bandgap energy, a process known as wavelength selection.
Describe stefans law with example
?
Stefan’s Law for Black Body Radiation
Introduction
Stefan’s Law, also known as the Stefan-Boltzmann Law, is a fundamental principle in thermal radiation that describes the power emitted per unit area by a black body in terms of its absolute temperature. A black body is an idealized object that absorbs all incident radiation and re-emits energy solely as a function of temperature. This law is crucial in various fields, including astrophysics, thermodynamics, and radiation physics.
Mathematical Expression
The Stefan-Boltzmann Law is given by:
E = \sigma T^4
where:
= Radiant energy flux (power per unit area) emitted by the black body ()
= Absolute temperature of the black body ()
= Stefan-Boltzmann constant, which has a value of:
\sigma = 5.670 \times 10^{-8} \text{ W/m}^2\text{K}^4
For a finite surface area , the total power radiated by a black body is:
P = \sigma A T^4
For a real surface (non-ideal black body), the law is modified by introducing the emissivity , which accounts for how efficiently a surface emits radiation:
P = \varepsilon \sigma A T^4
where . A perfect black body has , while real objects have lower emissivity values.
Physical Significance
- Temperature Dependence: The energy emitted by a black body increases exponentially with temperature (), meaning even a slight increase in temperature leads to a significant rise in radiation.
- Astrophysics Applications: Stars, including the Sun, can be approximated as black bodies, and Stefan’s Law helps determine their luminosity (total power output).
- Thermal Engineering: It is used in designing radiators, thermal shields, and understanding heat loss from objects.
- Climate Science: The Earth’s radiation balance and global warming studies use this law to estimate how much heat the Earth radiates into space.
Example: Application in Astrophysics
Determining the Luminosity of the Sun
The luminosity of a star (total power radiated) is given by:
L = \sigma A T^4
For the Sun:
Surface temperature: K
Radius of the Sun: m
Surface area of the Sun:
Substituting the values:
L_{\odot} = (5.670 \times 10^{-8}) \times (4\pi (6.96 \times 10^8)^2) \times (5778)^4
L_{\odot} \approx 3.846 \times 10^{26} \text{ W}
Thus, the Stefan-Boltzmann Law allows us to estimate the total energy output of the Sun, crucial for understanding stellar properties and energy transfer in the universe.
Conclusion
Stefan’s Law provides a powerful relationship between an object’s temperature and its radiated energy. It has widespread applications in physics, from understanding cosmic bodies to designing thermal systems. The law’s dependence on temperature to the fourth power makes it highly sensitive to temperature variations, making it a cornerstone of radiation physics and thermodynamics.
What does Wien’s Law state?
The peak wavelength of radiation emitted by a black body is inversely proportional to its absolute temperature.
What is Heisenberg’s Uncertainty Principle?
It states that it is impossible to simultaneously determine both position (Δx) and momentum (Δp) of a particle with absolute precision.
Formula:
Δ𝑥⋅Δ𝑝≥ℎ/4𝜋
Key Idea: The more precisely one quantity is measured, the more uncertain the other becomes.
What happens when the temperature of a black body increases?
The peak wavelength shifts to shorter wavelengths (higher energy, bluer light).
How are full-color images produced in LED displays?
Full-color displays typically use pixels composed of red, green, and blue sub-LEDs; varying the intensity of these three colors produces a wide range of colors through color mixing.
What happens when photons hit a solar cell?
Photons are absorbed by the semiconductor material (usually silicon), generating electron-hole pairs.
What is black body radiation?
Black body radiation is the electromagnetic radiation emitted by a black body. Its spectrum depends solely on the object’s temperature, and it serves as a fundamental model for understanding real-world emission.
How do defect states influence non-radiative recombination?
Defect states are imperfections in the crystal lattice that facilitate non-radiative recombination, causing energy to be lost as heat rather than as light.
What is Planck’s Law?
📝 Definition:
Planck’s Law describes how a blackbody emits electromagnetic radiation at different wavelengths based on its temperature.
formula:
E(λ)dλ=8(pi)hc/λ^(5) *(1/e^(hc/kbt) -1)
What is the main difference between plasma and LCD displays?
Plasma uses gas discharge to excite a phosphor coating, while LCD uses liquid crystals to control light from a backlighting source.
Where are Stefan’s and Wien’s Laws used?
Astrophysics: Determines star temperatures and luminosity.
Climate Science: Helps model Earth’s radiation balance.
Infrared Cameras: Used in thermal imaging and heat sensors.
How are the LEDs arranged in an LED display?
They are arranged in a matrix or grid format, where each LED (or group of LEDs) forms a pixel, enabling detailed image formation.
What is wave-particle duality?
Wave-particle duality is the concept in quantum mechanics that describes how particles, such as electrons and photons, exhibit both wave-like and particle-like properties depending on the experiment.
What is efficiency droop in LEDs?
Efficiency droop refers to the decrease in light output per electron at high current densities, an important factor to consider in high-power LED applications.
What is a black body in physics?
A black body is an idealized object that absorbs all incident electromagnetic radiation, regardless of frequency or angle, and emits radiation based solely on its temperature.
What is a Blackbody?
🖤 A blackbody is an ideal object that absorbs all radiation falling on it and emits radiation based only on its temperature.
📊 Key Feature: The color of emitted light depends on temperature.
Hotter → More blue light
Cooler → More red light
What are the main layers of an OLED display?
Anode (positive electrode)
Organic semiconductor layers
Cathode (negative electrode)
What is non-radiative recombination in semiconductors?
It is the process where an electron-hole pair recombines without emitting a photon; instead, the energy is dissipated as heat, often via defect states or phonon interactions.
What is the equation for Wien’s Law?
λ max = b/T
where:
λ
max
= Peak wavelength (m)
T = Absolute temperature (K)
b = Wien’s displacement constant (2.897×10 ^(−3)
m·K)
What is the role of scanning and multiplexing in LED displays?
Scanning and multiplexing techniques allow the display to refresh one row or column at a time rapidly, reducing the number of required driver circuits while still creating a stable, continuous image.
What is the significance of bandgap energy in a solar cell?
Bandgap energy is the minimum energy needed to free an electron from the valence band to the conduction band, allowing it to contribute to electrical conduction.
Give a real-world example of black body radiation.
The Cosmic Microwave Background (CMB) is a nearly perfect black body spectrum at a temperature of about 2.7 K, providing evidence for the Big Bang and insight into the early universe.
How do plasma displays create images?
Electricity excites noble gases (neon, xenon) in tiny cells, creating ultraviolet (UV) light, which then makes a phosphor coating glow in red, green, or blue to form images.
Where is the probability of finding a particle highest and lowest in the ground state ((n = 1)) of a quantum box?
- \textbf{Highest:} At ( x = \frac{a}{2} ) (middle of the box)
- \textbf{Zero:} At ( x = 0 ) and ( x = a ) (at the walls)
Probability density:
[
|\psi_1 (x)|^2 = \frac{2}{a} \sin^2\left(\frac{\pi x}{a}\right)
]
What are some real-world applications of OLED?
OLED is used in smartphones, TVs, smartwatches, VR headsets, and even foldable displays!
What is luminescence in the context of semiconductor recombination?
Luminescence is the emission of light resulting from radiative recombination, which is fundamental in devices like LEDs and laser diodes.
What is the mathematical expression of Stefan-Boltzmann Law?
E=σT ^4
where:
E = Total emitted energy per unit area (W/m²)
σ = Stefan-Boltzmann constant (
5.67×10^−8𝑊𝑚^(−2)k^(-4)
T = Absolute temperature in Kelvin
How does a CRT display work?
Uses an electron beam inside a cathode ray tube to excite phosphors, creating images.
What is the uncertainty relation for angular momentum and angular displacement?
ΔϕΔL z ≥ ℏ/4pi
Precise angle measurement (Δ𝜙) leads to high uncertainty in angular momentum (Δ𝐿𝑧).
Important in rotational spectroscopy and quantum angular motion.
Explain the working of an LED display
Full Definition of an LED Display:
An LED display is an electronic screen that uses an array of light-emitting diodes (LEDs) as individual pixels to create images, videos, or text by controlling the brightness and color of each LED in a coordinated manner.
Matrix Arrangement of LEDs:
The display consists of many LEDs arranged in a grid or matrix, where each LED or group of LEDs forms a pixel. This arrangement allows for the creation of detailed images by illuminating specific areas of the grid.
Scanning and Multiplexing Techniques:
To manage large numbers of pixels with fewer driver circuits, LED displays often use scanning or multiplexing methods. The display refreshes one row or column at a time rapidly, creating a continuous and stable image to the human eye.
Driver Circuitry and Control Signals:
Integrated driver circuits send precise electrical signals to each LED pixel. These signals control the on/off state and adjust the intensity of the LEDs, thereby forming the desired image or video content.
Individual LED Operation:
Each LED operates on the principle of forward biasing at a p-n junction, where electron-hole recombination releases energy as light. In the display, this process is managed collectively to produce coherent images.
Color Mixing in Full-Color Displays:
In full-color LED displays, each pixel is usually made up of red, green, and blue sub-LEDs. By varying the intensity of these three colors through modulation of the electrical signals, a wide spectrum of colors can be produced.
Define Weain’s law and black body ration with an example.
Wien’s Law
Definition:
Wien’s Law describes the relationship between the wavelength at which the emission of a black body is at its maximum and its temperature. In simple terms, it states that as the temperature of an object increases, the peak of its emitted spectrum shifts to shorter wavelengths.
Mathematical Expression:
The law is mathematically expressed as:
𝜆max⋅𝑇=𝑏
where:
𝜆max is the wavelength of peak emission,
T is the temperature in Kelvin, and
b is Wien’s constant (approximately
2.898×10^−3 m·K).
Significance:
Wavelength-Temperature Relationship: It clearly shows that the hotter an object, the smaller its 𝜆max
, meaning the peak shifts towards the blue end of the spectrum.
Practical Applications: This law is used in astrophysics to determine the temperature of stars and other celestial bodies by analyzing their emitted light.
Predictive Power: It provides a simple yet powerful predictive tool to infer physical properties (like temperature) from observed spectral data.
Example:
Consider the Sun, which has a surface temperature of approximately 5800 K. Using Wien’s Law, one can calculate the peak wavelength of its radiation. The peak falls in the visible range (around 500 nm), explaining why our eyes are most sensitive to the light emitted by the Sun.
Black Body Radiation
Definition:
Black Body Radiation refers to the theoretical spectrum of electromagnetic radiation emitted by an idealized object that absorbs all incident radiation, regardless of frequency or angle. This object is known as a black body.
Planck’s Law:
The spectral distribution of this radiation is governed by Planck’s law, which is given by:
𝐵(𝜆,𝑇)=2ℎ𝑐^(2)/𝜆^(5) *(1/𝑒^(ℎ𝑐/𝜆𝑘𝐵^(𝑇)) -1
where:
B(λ,T) is the spectral radiance,
h is Planck’s constant,
c is the speed of light,
λ is the wavelength,
B is Boltzmann’s constant, and
T is the temperature in Kelvin.
Significance:
Fundamental Insight: Black body radiation was crucial in the development of quantum mechanics, as classical theories failed to explain its observed spectrum.
Spectrum Analysis: The concept helps us understand how objects emit radiation and how the spectrum changes with temperature.
Universal Behavior: It provides a baseline or reference for the emission properties of real objects, even if they are not perfect black bodies.
Example:
A real-world example is the Cosmic Microwave Background (CMB) radiation. The CMB is a nearly perfect black body spectrum at a temperature of about 2.7 K, which provides strong evidence for the Big Bang theory and helps astrophysicists study the early universe.
Conclusion
Both Wien’s Law and Black Body Radiation are fundamental in understanding the emission of electromagnetic radiation:
Wien’s Law directly links the wavelength of peak emission with the temperature of an object.
Black Body Radiation, described by Planck’s law, details the entire spectrum of radiation emitted by an ideal object.
Energy Quantization
🔬 Key Idea: Planck discovered that energy is not continuous but comes in small, fixed packets called quanta.
⚡ Formula for energy of a quantum:
E=hν
where h = Planck’s constant and
ν = frequency of light.
🧩 Think of it like Lego blocks—you can’t break them into smaller pieces!
How does a solar cell achieve charge separation?
A built-in electric field at the p-n junction separates the electron-hole pairs: electrons move to the n-type side, and holes move to the p-type side.
“Compare the energy efficiency and color quality of LED and OLED displays
Technology
LED Displays: Use backlit technology; a light source illuminates the liquid crystal layer.
OLED Displays: Feature self-emissive pixels that generate their own light.
Energy Efficiency
LED: Generally efficient in bright scenes but consumes more power in dark images since the backlight remains on.
OLED: Offers higher power efficiency for darker images as pixels can be completely turned off, though bright scenes may use more power.
Color Quality
LED: Can struggle with deep blacks and contrast due to constant backlighting.
OLED: Delivers superior contrast ratio and more vibrant colors because each pixel is individually controlled.
How does a PIN photodetector work?
When light hits the intrinsic region, it generates electron–hole pairs (charge carriers). These carriers are swept out by the built-in electric field, producing a photocurrent directly proportional to the light intensity.
Why are LCD screens more common today?
They are thinner, lighter, more power-efficient, and suitable for a wide range of devices, from monitors to smartphones.
What is the impact of non-radiative recombination on semiconductor devices?
It leads to energy losses through thermal dissipation, reducing the efficiency of devices such as solar cells.
What is field emission?
A process where electrons are pulled from the cold cathodes by a strong electric field instead of heat.
What is the unique feature of an avalanche photodetector (APD) compared to a PIN photodetector?
An APD operates at a higher reverse bias voltage, which accelerates the charge carriers to high energies. This leads to impact ionization, where high-energy carriers create additional electron–hole pairs, resulting in photocurrent amplification.
The Ultraviolet Catastrophe
🚨 Problem (Before Planck’s Law):
Classical physics (Rayleigh-Jeans Law) predicted that as wavelength decreases, energy should increase infinitely—which didn’t match reality!
✨ Solution: Planck’s Law correctly showed that energy at short wavelengths drops off, solving the problem.
Compare the response times of PIN and avalanche photodetectors.
PIN photodetectors generally have a faster response time since they lack the additional delay from the multiplication process. In contrast, APDs may have a slightly slower response due to the time required for impact ionization.
What are nano-scale emitters in FED?
Ultra-small pointed structures that enhance field emission, making the display more efficient.
Why is black body radiation significant in physics?
It was crucial in the development of quantum mechanics, as classical physics couldn’t explain its observed spectrum. It also provides a reference for the emission properties of real objects and aids in studying the spectrum of stars and other celestial bodies.
How does the individual LED operate within the display?
Each LED functions on the principle of forward biasing at a p-n junction, where electrons and holes recombine to release energy in the form of light.
What are some common real-world applications of LED displays?
They are widely used in televisions, smartphones, digital billboards, traffic signals, and various digital signage systems due to their efficiency and vivid color production.
Which display type was commonly used in old TVs and monitors?
CRT – but it has been replaced by LCDs in modern devices.
What is the peak wavelength of the Sun?
λ
max =( 2.897×10
−3)/5800
≈500nm
This is in the visible range, explaining why the Sun appears yellow-white.
What is the normalized wave function for a particle in a 1D box of width (a)?
The normalized wave function is:
[
\psi_n(x) = \sqrt{\frac{2}{a}} \sin\left(\frac{n\pi x}{a}\right)
]
where ( n = 1, 2, 3, \dots ) represents different quantum states.
What does the de Broglie equation imply?
It implies that all moving particles, including electrons and atoms, have wave-like properties, with their wavelength inversely proportional to their momentum.
What is impact ionization and why is it important in APDs?
Impact ionization is a process where accelerated charge carriers collide with the lattice atoms, releasing more electron–hole pairs. This is the key mechanism for photocurrent amplification in avalanche photodetectors, allowing them to detect very low levels of light.
Why is Planck’s Law Important?
🚀 Planck’s Discovery Led To:
✅ Fixing the ultraviolet catastrophe
✅ The birth of quantum mechanics
✅ Einstein’s photoelectric effect explanation
✅ Understanding how atoms and light interact
🌎 Impact: It changed the way we understand physics and the universe at a microscopic level!
Where are plasma displays commonly used?
Large-screen TVs and home theater systems due to their better color accuracy and viewing angles.
