Solar Energy Multiple Choice Questions on “Solar Radiation Geometry – 1”.
1. What is angle subtended by sun on earth in degrees?
a) About 0.5 degrees
b) About 1 degree
c) About 35 degrees
d) About 5 degrees
Answer: a
Clarification: Sun subtends an angle of 32 minutes at earth’s surface. When converted to degrees, it comes out to be 0.53 degrees.
2. Why is angle subtended by sun on earth’s surface so small?
a) Because sun is smaller than earth
b) Because of the large distance between earth and sun
c) Because of the small distance between earth and sun
d) Because sun is about the same size as that of earth
Answer: b
Clarification: The angle subtended by sun on earth’s surface is about 0.53 degrees. It is so small because of the large distance between the earth and sun.
3. When revolving around the sun, the earth moves in an elliptical cycle _______
a) on the sun’s plane
b) above the sun’s plane
c) above and below the sun’s plane
d) below the sun’s plane
Answer: c
Clarification: When revolving around the sun, the earth moves in an elliptical path. The earth passes above and below the sun’s plane to complete an elliptical cycle.
4. Which month is the earth closes to the sun?
a) February
b) March
c) December
d) January
Answer: d
Clarification: Earth is closest to the sun in January. Specifically, earth is closes on January 3rd. The distance between earth and sun is approximately 147.3 million km.
5. What is aphelion?
a) The point where earth is farthest from the sun
b) The point where earth is nearest from the sun
c) The point where earth is on the perpendicular bisector of sun’s plane
d) The point when earth subtends an angle of 30 degrees with sun’s plane
Answer: a
Clarification: Aphelion is the point where earth is farthest from the sun. The point where earth is nearest to the sun is called perihelion.
6. Which month is the earth farthest from the sun?
a) June
b) July
c) August
d) January
Answer: b
Clarification: Earth is farthest from the sun in July. Specifically, it is farthest on 4th July. The distance between earth and sun is approximately 152.1 million km.
7. What is solstice?
a) The point where earth is farthest from the sun
b) The point where earth is nearest from the sun
c) When sun’s zenith is at its furthest point from celestial equator
d) When sun’s zenith is at its closest point from celestial equator
Answer: c
Clarification: Solstice occur when sun’s zenith is at its furthest point from celestial equator. It could either be the northerly zenith or the southerly zenith.
8. What is sun declination angle?
a) Angle between sun and earth
b) Angle between ray of the sun touching earth’s surface and the equatorial plane
c) Angle between an observer on earth and the celestial equatorial plane
d) Angle between ray of the sun when extended to the earth’s center and the equatorial plane
Answer: d
Clarification: Sun declination angle is the angle between ray of the sun when extended to the earth’s center and the equatorial plane. It is positively oriented when sun’s rays reach the center through northern hemisphere and negative when the sun’s rays reach through southern hemisphere.
9. What is sun’s declination angle during summer solstice?
a) 23.5 degrees
b) 0.53 degrees
c) 32 minutes
d) -23.5 degrees
Answer: a
Clarification: Sun’s declination angle during summer solstice is 23.5 degrees. Thus, the sun shines down on the Tropic of Cancer in the northern hemisphere.
10. What is sun’s declination angle during winter solstice?
a) 25 degrees
b) -23.5 degrees
c) 37 degrees
d) 23.5 degrees
Answer: b
Clarification: Sun’s declination angle during summer solstice is -23.5 degrees. Thus, the sun shines down on the Tropic of Capricorn in the southern hemisphere and remains below the horizon everywhere within Arctic Circle.
11. What is an equinox?
a) When earth is farthest from the sun
b) When earth is nearest to the sun
c) When earth’s center lies in the plane of sun
d) When earth’s center does not lie in the plane of sun
Answer: c
Clarification: An equinox occurs when the earth’s center lies on the plane of sun. There are two such occasions throughout the year. Perihelion is the point where earth is nearest to the sun. Aphelion is the point where earth is farthest from the sun.
12. Why does earth receive 12 hours of sunshine during equinox?
a) Because earth’s center lies on the plane of the sun
b) Because earth’s center does not lie on the plane of the sun
c) Because earth is nearest to the sun
d) Because earth’s axis is perpendicular to the plane of the sun
Answer: d
Clarification: During equinox, earth receives 12 hours of sunshine. This is mainly because earth’s north-south axis of rotation is perpendicular to the plane of the sun.
13. What is the sun’s declination angle during equinox?
a) 0 degrees
b) 1 degree
c) 13 degrees
d) 23.5 degrees
Answer: a
Clarification: Sun’s declination angle has a measure of 0 degrees on the days of equinox. The declination angle is 23.5 degrees during summer solstice and -23.5 degrees during winter solstice.
14. The equinoxes are vernal equinox and autumnal equinox respectively.
a) True
b) False
Answer: a
Clarification: The equinoxes are vernal equinox and autumnal equinox respectively. The sun has a 0 degree declination angle on these two days of the year.
15. On summer solstice, the sun is above the horizon in northern hemisphere.
a) True
b) False
Answer: a
Clarification: On summer solstice, the sun is above the horizon for longest period of time in northern hemisphere. Hence, it is the longest fay for daylight.
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