Test: GIS, GPS & Remote Sensing- 2 - Civil Engineering (CE) MCQ

Photons are the main constituent particles in the electromagnetic energy. The relation between velocity, wavelength and frequency is determined as λ = c / f, where λ represents wavelength, f is the frequency of the wave and c represents the velocity of the wave, which is equal to speed of light.

Electro-magnetic waves are used in case of remote sensing. The different waves present in this spectrum enables us to use a variety of waves based on the condition present and can be able have a better output.

Remote sensing involves certain principles which are applied for having a good result of the desired output. The principles are electromagnetic energy, electro-magnetic spectrum, interaction of energy with atmosphere etc.

A wide range of waves are present in case of electromagnetic spectrum, off which the gamma-rays are having a nano level wave length capacity i.e., less than 0.03nm.

Visible region consist of three color waves red, blue and green remaining are the combination of those. The blue light is having a wavelength range of 0.42-0.52 micrometer.

EM waves used two major sources of fields i.e., electric and magnetic fields. Both are placed orthogonal to each other in a wave pattern. The electric components are placed in vertical manner and magnetic components in horizontal manner.

Stefan- Boltzmann law is based on the radiation produced and emitted by the body. This can be mathematically represented by M = σ*T⁴. Here, α is the Stefan- Boltzmann constant, T is the absolute temperature, M is the spectral existence of the body.

Scattering involves in distribution of the light ray in more than two directions. It can be further classified as Rayleigh scattering, Mie scattering, non-selective scattering.

At present, the air-borne platforms in use are Dakota, AVRO and beach-craft. A sensor is mounted on them and is placed at an altitude which can be able to access the specified object.

Polar orbiting satellites are also known as sun-synchronous satellites, which are generally placed at an altitude range of 700-1500km from the ground level. These are able to deliver accurate information about the object which we need access to.