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A furnace wall consists of two layers. The inside layer of 450 mm is made of light weight bricks of thermal conductivity IW/m.K and outside layer of 900 mm is made of refractory of thermal conductivity 2W/m.K. The hot face of the inside layer is at temperature 1300 K and the cold face of the outer layer is at 400 K. The temperature at the interface between the two layers is . . . . . . . . K.
A
1000
B
850
C
700
D
600
Correct Answer:
600
A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness __________ metre.
A
0.01
B
0.1
C
0.25
D
0.5
What is the condition for a tree to be weight balanced. where a is factor and n is a node? >= a*weight and weight >= a*weight. b) weight >= a*weight and weight >= a*weight. c) weight >= a*weight and weight >= a*weight. d) weight is a non zero
A
weight >= a*weight and weight >= a*weight.
B
n.left
C
n.left
D
n.left
A flat wall of fire clay, 50 cm thick and initially at 25 degree Celsius, has one of its faces suddenly exposed to a hot gas at 950 degree Celsius. If the heat transfer coefficient on the hot side is 7.5 W/m2 K and the other face of the wall is insulated so that no heat passes out of that face, determine the time necessary to raise the center of the wall to 350 degree Celsius. For fire clay brick Thermal conductivity = 1.12 W/m K Thermal diffusivity = 5.16 * 10 -7 m2/s
A
43.07 hours
B
53.07 hours
C
63.07 hours
D
73.07 hours
The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K = 0.04 W/m.°K and thickness 0.16 m is 10 W/m
2
. The temperature of the inside wall is -5°C. The outside wall temperature is
A
25°C
B
30°C
C
35°C
D
40°C
Weight of Arun is 4/7 of the weight of Bablu. Weight of Bablu is 1/2 of the weight of Ram. Weight of Ram is 4 times of the weight of Deep. Weight of Deepis 1/9 of the weight of Ankit. Whose weight is more than the weight of Deep but less than the weight of Bablu?
A
Ankit
B
Arun
C
Ram
D
Deep
Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer co-efficient is 3k/l. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade?
A
35.5
B
43.75
C
81.25
D
48.25
The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m
-1
.°C
-1
respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m
-2
.°C
-1
. The rate of heat loss from the outer surface in W.m
-2
is
A
165.4
B
167.5
C
172.5
D
175
A composite flat wall of a furnace is made of two materials 'A' and 'B'. The thermal conductivity of 'A' is twice of that of material 'B', while the thickness of layer of 'A' is half that of B. If the temperature at the two sides of the wall are 400 and 1200°K, then the temperature drop (in °K) across the layer of material 'A' is
A
125
B
133
C
150
D
160
Read the following passage carefully and choose the most appropriate answer to the question out of the four alternatives.
The human eye is a complex part of the body that is used for seeing. Eyes enable people to perform daily tasks and to learn about the world that surrounds them. Sight, or vision, is a rapidly occurring process that involves continuous interaction between the eye, the nervous system, and the brain. When someone looks at an object, what he really sees is the light reflected from the object. This reflected light passes through the lens and falls on the retina of the eye. Here the light induces nerve impulses that travel through the optic nerve to the brain and then over other nerves to muscles and glands.
The eye is similar to a television camera. Both the eye and the television camera convert light energy to electrical energy. The eye converts light to nerve impulses that are interpreted by the brain as the sense perception called sight. A television camera converts light to electronic signals that are broadcast and transformed into light images in a television receiver. It is wonderful that human eyes blink an average of once every six seconds. This washes the eye with the salty secretion from the tear or lachrymal glands. Each tear gland is about the size and shape of an almond. These glands are situated behind the upper eyelid at the outer corner of the eye. After passing over the eye, the liquid from the gland is drained into the nose through the tear duct at the inner corner of the eye. The sense perception that the brain releases after the eye converts light to nerve impulses is known as
A
Blindness
B
Image
C
Sight
D
Glare
The main reinforcement in the toe of a T-shaped R.C. retaining wall is provided on
i) top face parallel to the wall
ii) top face perpendicular to the wall
iii) bottom face parallel to the wall
iv) bottom face perpendicular to the wall
The correct answer is
A
Only (ii) is correct
B
(i) and (ii) are correct
C
(iii) and (iv) are correct
D
Only (iv) is correct