Quantum Theory of Photons
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Quantum Theory of Photons

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Questions and Answers

What is Rayleigh scattering primarily dependent on?

  • Relative size of particles and radiation wavelength (correct)
  • Angle of incidence
  • Type of reflecting surface
  • Intensity of radiation

    • Which effect does scattering have in remote sensing?

  • Increases the detail in captured images
  • Alters the spectral signature of ground objects (correct)
  • Enhances the contrast of images
  • Eliminates noise in the data

    • What does the concept of spectral reflectance measure?

  • Total energy of the reflecting surface
  • Proportion of incident energy that is reflected (correct)
  • Energy loss as heat
  • Average color of the surface

    • Which characteristic is associated with diffuse reflection?

    <p>It reflects energy uniformly in all directions</p> Signup and view all the answers

    What do spectral reflectance curves represent?

    <p>Relationship between EM spectrum and % reflectance</p> Signup and view all the answers

    What type of sensors measure natural radiation emitted by a target or reflected from it?

    <p>Passive Remote Sensors</p> Signup and view all the answers

    Which sensor is specifically used for measuring sea surface temperature?

    <p>Advanced Very High Resolution Radiometer (AVHRR)</p> Signup and view all the answers

    Which of the following describes the operation of a pushbroom scanner?

    <p>Utilizes a line of sensing elements to gather data continuously</p> Signup and view all the answers

    What is the wavelength range for optical sensors?

    <p>0.3 to 14 mm</p> Signup and view all the answers

    What advantage do microwave sensors have compared to optical sensors?

    <p>They penetrate the atmosphere under various conditions.</p> Signup and view all the answers

    What is the definition of apogee in satellite orbits?

    <p>The point where the satellite is at its farthest distance from the earth.</p> Signup and view all the answers

    Which type of satellite altitude is considered low altitude?

    <p>Altitude less than 2000 km</p> Signup and view all the answers

    Which type of sensors are capable of looking at differences over time in their data analysis?

    <p>Passive Sensors</p> Signup and view all the answers

    What does the ground track of a satellite represent?

    <p>The projection of the satellite's orbit on the earth's surface.</p> Signup and view all the answers

    Which characteristic is NOT typically associated with satellite orbits?

    <p>Color Variation</p> Signup and view all the answers

    What is a common application for microwave sensors?

    <p>Studying sea ice and snow</p> Signup and view all the answers

    How is the inclination of an orbit measured?

    <p>In degrees from the equator in a clockwise direction.</p> Signup and view all the answers

    What is the purpose of overlap in satellite imagery?

    <p>To identify common areas in consecutive images along the flight path.</p> Signup and view all the answers

    What are photons described as in quantum theory?

    <p>Discrete packets of light energy</p> Signup and view all the answers

    What does Plank's equation Q = hν relate to?

    <p>The amount of energy carried by a photon</p> Signup and view all the answers

    Which of the following ranges corresponds to the visible spectrum of light?

    <p>0.4 - 0.73 micrometers</p> Signup and view all the answers

    How does the energy of a photon relate to its wavelength?

    <p>Energy is inversely proportional to wavelength</p> Signup and view all the answers

    What is a key characteristic of infrared radiation?

    <p>It is reflected and can be detected using electro-optical sensors</p> Signup and view all the answers

    Which type of radiation primarily affects remote sensing activities due to atmospheric absorption?

    <p>Gamma rays</p> Signup and view all the answers

    What is the primary source of electromagnetic radiation for remote sensing?

    <p>The sun</p> Signup and view all the answers

    Which of the following correctly categorizes thermal infrared radiation?

    <p>Emitted and can only be detected using electro-optical sensors</p> Signup and view all the answers

    What is the primary purpose of Panchromatic (PAN) sensors?

    <p>To collect data in a single band</p> Signup and view all the answers

    Which sensor type is specifically designed to gather oceanographic data across several bands?

    <p>Ocean Color Monitor (OCM)</p> Signup and view all the answers

    In which type of orbit do sun-synchronous satellites typically operate?

    <p>Near polar orbit</p> Signup and view all the answers

    What is a defining feature of geostationary satellites?

    <p>They remain stationary relative to a specific point on Earth's surface</p> Signup and view all the answers

    Which of the following sensors operates in the most bands for oceanographic applications?

    <p>Ocean Color Monitor (OCM)</p> Signup and view all the answers

    What kind of coverage can non-sun-synchronous orbits provide?

    <p>Varying coverage in tropics, mid-latitudes, or high latitudes</p> Signup and view all the answers

    What is the altitude range for sun-synchronous polar orbits?

    <p>500-1,500 km</p> Signup and view all the answers

    Which sensor type is used for passive remote sensing across multiple frequency bands?

    <p>Multi-frequency Scanning Microwave Radiometer (MSMR)</p> Signup and view all the answers

    Study Notes

    Quantum Theory and Photons

    • Light travels in discrete packets known as 'quanta' or 'photons', forming the basis of electromagnetic (EM) radiation.
    • Photons are massless particles that embody electromagnetic force and are emitted when matter is thermally excited.
    • Energy of a photon is quantified in electron volts, while energy transfer rate is referred to as flux, measured in watts.
    • Planck's equation (Q=hν) determines photon energy, where Q is energy in watts, h is Planck's constant (6.626 x 10^-34 J), and ν is the frequency.
    • Quantum energy is inversely related to wavelength: Q = hc / λ; shorter wavelengths correspond to higher energy photons.

    Electromagnetic Spectrum

    • The electromagnetic spectrum encompasses all frequencies of EM radiation, presenting useful wavelength bands.
    • Visible light ranges: Blue (0.4 - 0.5 μm), Green (0.5 - 0.6 μm), and Red (0.6 - 0.7 μm).
    • Infrared (IR) is classified into Near IR (0.7 - 1.3 μm), Mid IR (1.3 - 3.0 μm), and Thermal IR (3.0 - 14 μm).
    • Microwaves range from 1 mm to 1 m; UV light at 0.4 μm is minimally utilized in remote sensing due to atmospheric scattering.

    Scattering and Its Effects

    • Scattering involves unpredictable diffusion of radiation by atmospheric particles, affecting remote sensing by reducing image contrast and altering spectral signatures.
    • Rayleigh scattering occurs with atmospheric molecules; diffuse reflectance describes equal scattering of reflection, crucial for understanding terrain properties.

    Spectral Signature Concept

    • Spectral reflectance measures the proportion of reflected energy relative to incident energy, expressed as a percentage.
    • Reflectance curves graph % reflectance against wavelength, highlighting specific material characteristics.

    Passive Remote Sensing

    • Passive remote sensing relies on natural or reflected radiation from targets, exemplified by sensors like the Advanced Very High Resolution Radiometer (AVHRR) and SeaWiFS.

    Sensor Types Based on Scanning Process

    • Whiskbroom scanners use rotating mirrors to achieve point sensing (e.g., Landsat MSS).
    • Pushbroom scanners utilize line arrays of sensors, allowing simultaneous data collection (e.g., SPOT).

    Sensor Types Based on EMR Range

    • Optical Sensors operate in the optical spectrum (0.3 to 14 mm) for applications like meteorology and ocean monitoring.
    • Microwave Sensors function in the microwave spectrum, effective under diverse atmospheric conditions, yet less reliable for identifying water bodies.

    Characteristics of Satellite Orbits

    • Orbital parameters include orbital period, altitude (low, moderate, or high), apogee, perigee, inclination (commonly 99 degrees for remote sensing), nadir, and ground track projections.
    • Swath refers to the area sensed during a satellite pass; overlap and sidelap denote common areas in consecutive images.

    Satellite Sensor Types

    • Linear Self-scanning Sensors (LISS) for multispectral scanning with various generations (LISS-I to LISS-IV).
    • Panchromatic (PAN) sensors collect single-band data; Advanced Wide Field Sensors (AWiFS) enable wide swath observations.
    • Variants include Ocean Color Monitor (OCM) and Synthetic Aperture Radar (SAR) for active microwave remote sensing.

    Orbit Types

    • Sun-synchronous orbits maintain consistent solar illumination conditions for imagery acquired at specific times across different seasons.
    • Polar-orbiting satellites capture data while the Earth rotates beneath them.
    • Geostationary satellites remain stationary over a specific point for continuous regional coverage.

    Applications of Remote Sensing

    • Remote sensing imagery can depict various environmental features, evidenced by the optical image of Montreal during the ice storm of 1998, where ice/snow/clouds and vegetation colors are identifiable.

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    Description

    Explore the fundamental concepts of quantum theory as it applies to the motion of light. This quiz covers the nature of photons, their energy representation, and how they relate to electromagnetic forces. Test your understanding of key principles like energy flux and thermal excitation.

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