Engineering :: Renewable Sources of Energy

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131.

Biot number signifies

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

132.

The diffuse radiation may be assumed to be equivalent to beam radiation coming at an angle of incidence of

A.	30?C	B.	45?C
C.	60?C	D.	90?C

133.

In a shell and tube heat exchanger the baffles are used

A.	to provide mixing of the fluid	B.	to deflect the flow in a particular direction
C.	to reduce the fouling of the tube surface	D.	to reduce the pressure drop

134.

Glass is the most favoured material for the transparent covers to be used in flat-plate collectors. The usual practice is to have 1 or 2 covers with spacings in the range of

A.	0.2 - 0.4 CM	B.	5 - 10 cm
C.	1.5 - 3 cm	D.	15-20 cm

135.

For zenith angles from 0? to 70? at sea level air mass m is given by where ?z is zenith angle

A.	m = cos ?z	B.	m = 1/cos ?z
C.	m = sin ?z	D.	m = 1/sin ?z

136.

For zenith angle of 60? at sea level air mass is

A.	0	B.	1
C.	2	D.	3

137.

Which radiation is not dangerous ?

A.	Cosmic radiation	B.	X-ray radiation
C.	Infrared radiation	D.	ultraviolet radiation

138.

Which of the following statements about light is incorrect?

A.	Light is energy	B.	Light cannot travel through vacuum
C.	Light travels in waves	D.	Velocity of light is greater than the velocity of sound

139.

The present theory of how the suns evergy is produced is based on Einsteins discovery of the relationship between

A.	energy and gravity	B.	matter and gravity
C.	gravity and light	D.	energy and matter

140.

The Carnot refrigeration cycle

A.	transfers energy from a low level of temperature to a high level of temperature	B.	requires the addition of external work for its operation
C.	performs the reverse effect of the heat engine	D.	all of the above