The winter solstice occurs on about
A.21-Nov
B.21-Jan
C.22-Dec
D.31-Dec
A.21-Nov
B.21-Jan
C.22-Dec
D.31-Dec
A.Ibn sin ?
B.Ibn cos ?
C.Ibn sec ?
D.Ibn
A.700 kg m-2
B.7000 kg m-2
C.70000 kg m-2
D.70 kg m-2
A.the ratio of heat conducted to heat convected
B.the ratio of heat convected to heat conducted
C.the ratio of external convective resistance to internal conductive resistance
D.none of the above
A.the declination angle is zero
B.the time during which the sun is visible is 12 hours
C.the time during which the sun is not visible is 12 hours
D.all of the above
A.because of the absorption of solar radiation on the earths surface and in the atmosphere
B.because of the rotation of the earth about its axis and its motion around the sun
C.both a and b
D.neither a nor b
A.of higher cycle efficiency
B.it has high heat transfer capability
C.it is inert
D.all of the above
A.Use of movable insulation to cover the collector
B.Drain the collector when it is not operating during periods of low ambient temperatures
C.Circulate an antifreeze solution rather than water
D.Increase the rate of water flow through the collector by a factor of 2 leaving it on at all times