# Solar Energy Questions and Answers – Solar Radiation Geometry – 2

This set of Solar Energy Multiple Choice Questions & Answers (MCQs) focuses on “Solar Radiation Geometry – 2”.

1. Which of the following best describes the motion of sun from autumnal equinox to winter solstice?
a) Earth is above the plane of the sun
b) Earth is below the plane of the sun
c) Earth’s center lies on the plane of the sun
d) Earth first escalates above the plane and then transcends below the plane of sun

Explanation: Earth is above the plane of the sun during its motion from autumnal equinox and winter solstice. Equinox occurs when the earth’s center lies on the plane of the sun. However, it doesn’t always lie on the plane of the sun throughout the year.

2. What is sun’s declination angle during earth’s motion from autumnal equinox to winter solstice?
a) Greater than 90 degrees
b) Less than 0 degrees
c) Greater than 0 degrees
d) Between 60 and 90 degrees

Explanation: Sun’s declination angle during earth’s motion from autumnal equinox to winter solstice to vernal equinox is less than 0 degrees. This is because the earth is above the plane of the sun.

3. During which of the following periods is the earth below the plane of sun?
a) Vernal equinox to winter solstice
b) Winter solstice to vernal equinox
c) Vernal equinox to summer solstice
d) Summer solstice to winter solstice

Explanation: The earth is below the plane of sun during its motion from vernal equinox to summer solstice and back to autumnal equinox. The earth is above the sun’s plane during its motion from winter solstice to vernal equinox.

4. What is the sun’s declination during earth’s motion from vernal equinox to summer solstice?
a) Greater than 50 degrees
b) Between 0 and 30 degrees
c) Greater than 0 degrees
d) Less than 0 degrees

Explanation: The sun’s declination angle during earth’s motion from vernal equinox to summer solstice is less than 0 degrees. This is because the earth is below the plane of the sun.

5. How is latitude of a location on earth defined?
a) Angle between line joining the location to earth’s center and earth’s equatorial plane
b) Angle between line joining the location to earth’s center and the meridian plane
c) Angle subtended by sun on earth
d) Angle between sun’s rays extended to earth’s center and earth’s equatorial plane

Explanation: Latitude of a location on earth is defined by the angle between line joining the location to earth’s center and earth’s equatorial plane. Sun’s declination angle is the angle between sun’s rays extended to earth’s center and earth’s equatorial plane.

6. The lines joining North and South pole of earth are called _____
a) latitudes
b) longitudes
c) equator
d) semicircle lines

Explanation: The lines joining North and South pole of earth are called lines of longitudes. They are semicircular because they run along the curved surface of earth.

7. When does the autumnal equinox occur?
a) January
b) August
c) September
d) December

Explanation: Autumnal equinox occurs in the month of September. Specifically, it occurs either on 22nd September or on 23rd September. Winter solstice occurs in December.

8. When does the vernal equinox occur?
a) January
b) December
c) September
d) March

Explanation: Vernal equinox occurs in the month of March. Specifically, it occurs on 20th or 21st March. September is the month of autumnal equinox.

9. Solar radiation spectrum is close to _____
a) that of a black body
b) that of a white body
c) that of Jupiter
d) that of phase response

Explanation: Solar radiation spectrum is close to that of a black body. The temperature is about 5800K. Phase response is talks about the delay of a (an electronic) system with frequency. Though it is not related to solar radiation, it is used to analyse many solar energy harvesting systems.

10. Which of the following indicates the position of any point on earth?
a) Rectangular co-ordinate system
b) Latitudes, longitudes
d) Spherical co-ordinate system

Explanation: Latitudes and longitudes are used to indicate the position of any point on the surface of the earth. Usage of spherical co-ordinate system depends on the application. Moreover, earth is not entirely spherical.

11. What is the range of sun’s declination angle throughout the year?
a) Between 0 and 90 degrees
b) Between 0 and 23.5 degrees
c) Between -23.5 and 23.5 degrees
d) Between -23.5 and 0 degrees

Explanation: Sun’s declination angle lies in the range of -23.5 and 23.5 degrees. It is positive when the earth is below the sun and negative when the earth is above the sun.

12. What the hour angle?
a) Angle between ray of the sun when extended to the earth’s center and the equatorial plane
b) Angle between line joining the location to earth’s center and earth’s equatorial plane
c) Angle through which the turns to bring the meridian of a point in line with sun’s rays
d) Angle through which the turns to bring the meridian of a point directly in line with sun’s rays

Explanation: Hour angle is the angle through which the turns to bring the meridian of a point directly in line with sun’s rays. Declination angle is angle between ray of the sun when extended to the earth’s center and the equatorial plane. Latitude is angle between line joining the location to earth’s center and earth’s equatorial plane.

13. Altitude angle is the _______
a) vertical angle between projection of sun’s rays on the horizontal plane of earth’s surface
b) horizontal angle between projection of sun’s rays on the horizontal plane of earth’s surface
c) vertical angle between projection of sun’s rays on the vertical plane normal to earth’s surface
d) horizontal angle between projection of sun’s rays on the vertical plane normal to earth’s surface

Explanation: Altitude angle is the vertical angle between projection of sun’s rays on the horizontal plane of earth’s surface. It is important to note that the angle is between the project of sun’s rays on the horizontal plane and not the ray its.

14. Hour angle is a measure of time of day with respect to solar noon.
a) True
b) False

Explanation: Hour angle is a measure of time of day with respect to solar noon. At noon, the hour angle is 0 degrees and rotates at 15 degree per hour.

15. The altitude angle is maximum at noon.
a) True
b) False

Explanation: The altitude angle talks about how high the sun appears in the sky. It is maximum at noon. It is zero at sunrise and sunset and is 90 degrees (maximum) at noon.

Sanfoundry Global Education & Learning Series – Solar Energy.

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