Multiple Choice Questions and Answers on Elements of Remote Sensing
01. Pick up the correct statement from the following:
(A) Topology describes the geometric characteristic of objects which do not change under transformations and are independent of any coordinate system
(B) Topological characteristics of an object are independent of scale measurement
(C) The three elements of topology are adjacency, containment, and connectivity
(D) All of these
Answer: Option D
02. Pick up the correct statement from the following:
(A) In remote sensing technique, the observation place, is called a platform
(B) Platforms may be either stationary or mobile
(C) Spatial resolution of the imaging system becomes poorer with increase of platform height
(D) All of these
Answer: Option D
03. Formation of snow occurs if the cloud temperature is
(A) Just above the freezing point
(B) At the freezing point
(C) Below the freezing point
(D) None of these
Answer: Option C
04. In the given figure the phase of
(A) Crest A is π/2
(B) B crossing is π
(C) Trough C is 3π/2
(D) All of these
Answer: Option D
05. Coherence of two electromagnetic waves takes place if their phase difference is:
(A) Constant in time
(B) Constant in space
(C) Constant in time and space
(D) None of these
Answer: Option C
06. Pick up the correct statement from the following:
(A) Indian space effort started in 1962 with the establishment of a rocket
(B) Development of space (DOS) was established by the Government of India in 1972
(C) Indian Space Research Organisation (ISRO) is responsible for the space technology and its application to various activities
(D) All of these
Answer: Option D
07. Pick up the correct statement from the following:
(A) For the same feature, the photograph taken from the satellite vertically above the aircraft, the height displacement is lesser than the aerial photograph
(B) The scale of the aerial photograph depends upon the scale of the topography
(C) The feature at the principal point has no height displacement
(D) All of the above
Answer: Option D
08. The coherence length over which there is a strong relationship between amplitudes is;
(A) Directly proportional to the bandwidth
(B) Inversely proportional to the bandwidth
(C) The square of the bandwidth
(D) None of these
Answer: Option B
09. The reflectance from a surface is called specular reflection if it follows:
(A) Snell’s law
(B) Lambert’s cosine law
(C) Planktan’s law
(D) All of these
Answer: Option A
10. Pick up the correct statement from the following:
(A) A graphical representation of spectral reflectance verses the various growth stages of a crop, depicts a phonologic pattern
(B) The changes in the polarisation of the radiation reflected or emitted by an object, is known as polarisation variation
(C) The degree of polarisation is a characteristic of the object which helps in the identification of the object
(D) All of these
Answer: Option D
11. Repetitive observations of the same area at equal interval of time are useful to monitor the dynamic phenomena:
(A) Cloud evolution
(B) Vegetative cover
(C) Snow cover
(D) All of these
Answer: Option D
12. Which one of the following parameters is considered to determine the reflectance of a vegetation canopy?
(A) Solar zenith angle
(B) Azimuth angle
(C) Look angle
(D) All of these
Answer: Option D
13. A perfectly black body:
(A) Is a diffuse emitter
(B) Absorbs all the radiations of every wave lengths
(C) Emits power of every wave length
(D) All the above
Answer: Option D
14. If θ is the angle of scan measured from the nadir, the ground distance swept by the sensor IFOV is proportional to:
(A) sin2θ
(B) cos2θ
(C) sec2θ
(D) tan2θ
Answer: Option C
15. Which one the following is a correct statement?
(A) The vertical section of the soil extending into the parent material, is called profile
(B) The layers of the soil parallel to the earth surface are called horizons
(C) The transitional layer between two adjoining horizons is called boundary
(D) All of these
Answer: Option D
16. In case of reflection and refraction of electromagnetic radiation,
(A) Angle of incidence = angle of refraction
(B) Angle of incidence = angle of reflection
(C) Angle of refraction = sum of the angles of incidence and refraction
(D) All the above
Answer: Option B
17. Pick up the correct statement from the following:
(A) The minimum frequency of light for which no electrons are emitted, is called threshold frequency
(B) Polarising angle of glass is 57.5°
(C) At the polarising angle, the reflected and refracted rays are orthogonal
(D) All the above
Answer: Option D
18. Which one of the following factors does not affect the scale of the air photographs?
(A) Focal length
(B) Flying height
(C) Ground elevation
(D) None of these
Answer: Option D
19. Which one of the following statements regarding remote sensing is correct?
(A) The interaction of the electromagnetic radiation with the target
(B) The emission of electromagnetic radiation from the target
(C) Both (a) and (b)
(D) Neither (a) nor (b)
Answer: Option C
20. The optical property of a water body depends on:
(A) Absorption by the dissolved material
(B) Absorption by the suspended particulate matter
(C) Scattering by the suspended particulate matter
(D) All of these
Answer: Option D
21. Pick up the correct statement from the following:
(A) Frequency is the number of wave crests passing a fixed point in one second
(B) Frequency of a wave is measured in Hertz (Hz)
(C) Amplitude of a wave is the height of its crust from the mid-point
(D) All of these
Answer: Option D
22. The object of photo-interpretation is:
(A) Identification
(B) Recognition of objects
(C) Judging the significance of objects
(D) All of these
Answer: Option D
23. Pick up the correct statement from the following:
(A) Phytoplankton contains photosynthetically active pigment
(B) An increase of phytoplankton increases the back scattering in the green region
(C) An increase of phytoplankton absorbs the bule region rapidly
(D) An increase of phytoplankton decreases the back scattering in the green region
Answer: Option D
24. Which one of the following statements is correct regarding the GPS satellites?
(A) The nominal altitude is about 20,200 km
(B) The inclination of axis satellite is 55°
(C) The satellite transmits two L band signals (L1 with 1575.42 MHz and L2 with 1276.6 MHz)
(D) All of these
Answer: Option D
25. Which one of the following statements is correct?
(A) During the day, earth reflects solar radiation
(B) During the day, earth reflects both solar radiations the emission from its surface
(C) During the night, earth emits radiation from its surface
(D) All of these
Answer: Option D
26. A reduction of nitrogen nutrient in plants:
(A) Affects leaf colour
(B) Reduces pigment concentration
(C) Increase the visible reflectivity
(D) All of these
Answer: Option D
27. Remote sensing techniques make use of the properties of ___________ emitted, reflected or diffracted by the sensed objects:
(A) Electric waves
(B) Sound waves
(C) Electromagnetic waves
(D) Wind waves
Answer: Option C
28. Which one of the following statement is incorrect regarding the electromagnetic radiation?
(A) These are produced by the motion of electric charge
(B) The oscillation of charged particles sets up changing electric fields
(C) The changing electric fields induce the changing magnetic fields in the surrounding medium
(D) None of these
Answer: Option D
29. The altitudinal distance of a geostationary satellite from the earth is about:
(A) 26,000 km
(B) 30,000 km
(C) 36,000 km
(D) 44,000 km
Answer: Option C
30. The ratio of the total solar radiant energy returned by a planetary body to the total radiant energy incident on the body, the called:
(A) Reflectance
(B) Reflectance factor
(C) Albedo
(D) None of these
Answer: Option C
31. Due to scan geometry of a satellite sensor:
(A) The off-nadir resolution is degraded
(B) The ground distance swept by the senor, IFOV is proportional to sec2θ, where θ is the angle of scan measured from the nadir
(C) The details towards the edge of the scan get compressed
(D) All of these
Answer: Option D
32. Which one of the following statement is correct?
(A) Radiant energy expressed in Joules, is the energy associated with electromagnetic radiation
(B) The rate of transfer of radiant energy is called flux and is expressed in watts
(C) The radiant energy which falls upon a surface is termed as irradiance
(D) All of these
Answer: Option D
33. Which one of the following parameters is accurate for DGPS?
(A) Positional accuracies ~ 1 – 2 m if rover is less than 1-2 km from the reference station
(B) Positional accuracies ~ 2 – 5m if rover is less than 2-5 fm from the reference station
(C) Positional accuracies ~ 5 – 10 m if rover is less than 5-10 km from reference station
(D) Positional accuracies ~ 5 – 10 m if rover is less than 25 km
Answer: Option A
34. Pick up the correct statement from the following:
(A) The surface defined by the locus of points having same phase, is called a wave front
(B) The wave whose surface of constant phase are parallel planes, is known as a plane wave
(C) The relative phase difference between the waves is important and not the absolute phase of a point on the wave (D) All of these
Answer: Option D
35. Which one of the following statements is correct?
(A) π radians equal to 180°
(B) The cone subtended by an area on the sphere at the centre, is called the solid angle
(C) The solid angle is equal to the ratio of the area on the sphere and the square of the radius of the sphere
(D) All of these
Answer: Option D
36. Crop Acreage and Production Estimation (CAPE) was funded and taken up in 1983 by:
(A) USA
(B) European Union
(C) Russia
(D) India
Answer: Option D
37. ‘A time varying electric field produces a magnetic field.’ This phenomenon is called:
(A) Hertz’s law
(B) Ampere Maxwell’s law
(C) Faraday’s law
(D) Kirchoff’s law
Answer: Option B
38. The changes in the reflectivity/emissivity with time, is called:
(A) Spectral variation
(B) Spatial variation
(C) Temporal variation
(D) None of these
Answer: Option C
39. Which one of the following statements is correct?
(A) Snow albedo falls at all wave length with the increase of grain size
(B) The effect of grain size on reflection is maximum in the near-IR region
(C) The effect of grain size on reflection is low in the visible region of the spectrum
(D) All of these
Answer: Option D
40. Due to perturbation of the orbit, satellite orbit parameters are frequently updated on measurements carried out by its
(A) Six ground stations
(B) Five ground stations
(C) Four ground stations
(D) Three ground stations
Answer: Option B
41. Which one of the following helps to identify the objects on the earth surface?
(A) Atmospheric window
(B) Signature
(C) Radiometric error
(D) None of these
Answer: Option B
42. Pick up the correct statement from the following:
(A) Phase of a wave is expressed as a fraction of a period with respect to a reference
(B) Phase is usually specified by angular measure with one period being 360°
(C) The reference for finding the phase of a wave is taken from the previous passage through zero from the negative to the positive direction
(D) All of these
Answer: Option D
43. The reflection of solar energy is characterised by the water content in the leaf, in the reflective optical infrared:
(A) Visible (0.4 – 0.7 μm) region
(B) Near-IR (0.7 – 1.3 μm) region
(C) Short wave-IR (1.3 – 2.7 μm) region
(D) None of these
Answer: Option C
44. The interaction of the electromagnetic radiation produced with a specific wave length to illuminate a target on the terrain for studying its scattered radiance, is called:
(A) Passive remote sensing
(B) Active remote sensing
(C) Neutral remote sensing
(D) None of these
Answer: Option B
45. For interpolation of satellite data used for monitoring dynamic changes that occurs on the earth surface, the most suitable orbit for the satellite is:
(A) Circular orbit
(B) Sun-synchronous orbit
(C) Near polar orbit
(D) None of these
Answer: Option B
46. Electromagnetic spectrum contains:
(A) Gamma rays (wave length < 10-10 m)
(B) Ultraviolet rays (wave length < 10-6 m)
(C) Infrared rays (wave length < 10-4 m)
(D) All of these
Answer: Option D
47. Which one of the following quantities forms the basis of radiometry?
(A) Radiant energy (Q)
(B) Radiant flux (φ)
(C) Radiant intensity (I)
(D) All of these
Answer: Option D
48. According to the Snell’s law if an electromagnetic wave is incident in a medium (refractive index n1) on another medium (refractive index m2);
(A) The angle of incidence is equal to the angle of refraction
(B) The angle of refraction (θr) is given by sin θ₂ = (n₁/n₂) sin θi
(C) Both (a) and (b)
(D) Neither (a) nor (b)
Answer: Option B
49. The refractive index of the ocean water:
(A) Increases with salinity
(B) Increases with temperature
(C) Decreases with salinity
(D) Decreases with temperature
Answer: Option A
50. The phase difference of the waves 1 and 2 at A in the given figure is:
(A) π/4
(B) π/2
(C) π
(D) 3π/2
Answer: Option B