200950 + Mcqs in General Page 39 McqOptions

1901.	Metals are good conductors of electricity because___.
A.	they contain free electrons
B.	the atoms are lightly packed
C.	they have high melting point
D.	All of the above
Answer» B. the atoms are lightly packed

Discussion

1902.	Planets do not twinkle because___
A.	they emit light of a constant intensity
B.	their distance from the earth does not change with time
C.	they are very far away from the earth resulting in decrease in intensity of light
D.	they are nearer to earth and hence we receive a greater amount of light and, therefore minor variations in the intensity are not noticeable
Answer» E.

Discussion

1903.	Stars appears to move from east to west because____
A.	all stars move from east to west
B.	the earth rotates from west to east
C.	the earth rotates from east to west
D.	the background of the stars moves from west to east
Answer» C. the earth rotates from east to west

Discussion

1904.	Mirage is due to__
A.	unequal heating of different parts of the atmosphere
B.	magnetic disturbances in the atmosphere
C.	depletion of ozone layer in the atmosphere
D.	equal heating of different parts of the atmosphere
Answer» B. magnetic disturbances in the atmosphere

Discussion

1905.	Nuclear sizes are expressed in a unit named?
A.	Fermi
B.	angstrom
C.	newton
D.	tesla
Answer» B. angstrom

Discussion

1906.	Light year is a unit of?
A.	Time
B.	Distance
C.	Light
D.	Intensity of light
Answer» C. Light

Discussion

1907.	Light from the Sun reaches us in nearly__.
A.	2 minutes
B.	4 minutes
C.	8 minutes
D.	16 minutes
Answer» D. 16 minutes

Discussion

1908.	The absorption of ink by blotting paper involves_____.
A.	viscosity of ink
B.	capillary action phenomenon
C.	diffusion of ink through the blotting
D.	siphon action
Answer» C. diffusion of ink through the blotting

Discussion

1909.	Large transformers, when used for some time, become very hot and are cooled by circulating oil. The heating of the transformer is due to____.
A.	the heating effect of current alone
B.	hysteresis loss alone
C.	both the heating effect of current and hysteresis loss
D.	intense sunlight at noon
Answer» D. intense sunlight at noon

Discussion

1910.	Siphon will fail to work if____.
A.	the densities of the liquid in the two vessels are equal
B.	the level of the liquid in the two vessels are at the same height
C.	both its limbs are of unequal length
D.	the temperature of the liquids in the two vessels are the same
Answer» C. both its limbs are of unequal length

Discussion

1911.	It is easier to roll a stone up a sloping road than to lift it vertical upwards because__.
A.	work done in rolling is more than in lifting
B.	work done in lifting the stone is equal to rolling it
C.	work done in both is same but the rate of doing work is less in rolling
D.	work done in rolling a stone is less than in lifting it
Answer» E.

Discussion

1912.	Wien’s constant units is?
A.	m.k
B.	kg
C.	m.m
D.	mg.
Answer» B. kg

Discussion

1913.	Radiocarbon is produced in the atmosphere as a result of____
A.	collision between fast neutrons and nitrogen nuclei present in the atmosphere
B.	action of ultraviolet light from the sun on atmospheric oxygen
C.	action of solar radiations particularly cosmic rays on carbon dioxide present in the atmosphere
D.	lightning discharge in atmosphere
Answer» B. action of ultraviolet light from the sun on atmospheric oxygen

Discussion

1914.	The unit of Stefan’s constant is?
A.	watt/m2 K4
B.	watt/m3 K
C.	watt/m2 K
D.	watt/m3 K4
Answer» B. watt/m3 K

Discussion

1915.	A body at higher temperature T°K radiates heat at a rate which is proportional to ?
A.	T
B.	T2
C.	T-4
D.	T4
Answer» E.

Discussion

1916.	If a black body is heated from 27°C to 927°C. then the ratio of radiation emitted will be ?
A.	1: 4
B.	1: 16
C.	1: 8
D.	1: 256
Answer» E.

Discussion

1917.	A sphere cube and a thin circular plate all made of the same material and having the same mass are initially heated to a temperature of 300°C. Which of these cools fastest?
A.	Sphere
B.	Cube
C.	Plate
D.	None of these
Answer» D. None of these

Discussion

1918.	A black body emissive power is 81 J/m2 sec .It is at 300 K .Another one ordinary body emissivity is 0.8 it is at 500 K .then what is the emissive power of ordinary body?
A.	200 J/m2 sec
B.	300 J/m2 sec
C.	400 J/m2 sec
D.	500 J/m2 sec
Answer» E.

Discussion

1919.	Radiation emitted by a surface is directly proportional to ____.
A.	Third power of its temperature
B.	Equal to its temperature
C.	Twice power of its temperature
D.	Fourth power of its temperature
Answer» E.

Discussion

1920.	Two spheres made of same material have radii in the ratio 2: 1. If both the spheres are at same temperature, then what is the ratio of heat radiation energy emitted per second by them?
A.	1: 4
B.	4: 1
C.	3: 4
D.	4: 3
Answer» C. 3: 4

Discussion

1921.	A body cools from 100°C to 70°C in 8 minutes. If the room temperature is 15°C and assuming Newton’s law of cooling holds good, then time required for the body to cool from 70°C to 40°C is ?
A.	14 s
B.	10 s
C.	8 s
D.	5 s
Answer» B. 10 s

Discussion

1922.	Coefficient of transmission and coefficient of reflection for a given body are 0.22 and 0.74 respectively.Then, at a given temperature, the coefficient of emission for the body is ?
A.	0.4
B.	0.04
C.	0.96
D.	0.22
Answer» C. 0.96

Discussion

1923.	According to Prevost’s theory of heat exchange, the heat exchange shops at ?
A.	0°C
B.	- 5°C
C.	- 273°C
D.	- 273 K
Answer» D. - 273 K

Discussion

1924.	Unit of Stefan’s constant is given by ?
A.	W/ m K2
B.	W/ m2 K2
C.	W2/ m2 K4
D.	W/ mK
Answer» C. W2/ m2 K4

Discussion

1925.	The flow of heat from a hot body to a cold body is an example of?
A.	Isothermal process
B.	Reversible process
C.	Adiabatic process
D.	Irreversible process
Answer» E.

Discussion

1926.	For which of the following process, the thermal conduction is maximum?
A.	Combustion
B.	Radiation
C.	Convection
D.	Conduction
Answer» C. Convection

Discussion

1927.	A person with dark skin as compared to a person with white skin will experience ?
A.	Less heat and less cold
B.	More heat and more cold
C.	More heat and less cold
D.	Less heat and more cold.
Answer» C. More heat and less cold

Discussion

1928.	A perfectly black body emits radiation at temperature T1 K.If it is to radiate 16 times this power, its temperature T2 will be?
A.	T2 = 16 T1
B.	T2 = 8 T1
C.	T1 = 4 T1
D.	T2 = 2 T1
Answer» E.

Discussion

1929.	A black body at hot temperature at 227°C radiates heat at a rate of 5 cal/cm2 s. at a temperature of 727°C the rate of heat radiated per unit area will be?
A.	50 cal/cm2 s
B.	250 cal/cm2 s
C.	80 cal/cm2 s
D.	100 cal/cm2 s
Answer» D. 100 cal/cm2 s

Discussion

1930.	In which process the rate of transfer of heat is maximum?
A.	Conduction
B.	Convection
C.	Radiation
D.	In all these heat is transferred with the same velocity
Answer» D. In all these heat is transferred with the same velocity

Discussion

1931.	Two spheres made of same material have radii in the ratio 2:1. if both the spheres are at same temperature, then what is the ratio of heat radiation energy emitted per second by them?
A.	1: 4
B.	4: 1
C.	3: 4
D.	4: 3
Answer» C. 3: 4

Discussion

1932.	A body cools from 60°C to 50°C in 10 minutes. If the room temperature is 25°C and assuming Newton’s law of cooling to hold good, the temperature of the body at the end of the next 10 minutes will be ?
A.	38.5°C
B.	40°C
C.	42.85°C
D.	45°C
Answer» D. 45°C

Discussion

1933.	The velocity with which thermal radiation travels in vacuum is?
A.	3 ´ 106 m/s
B.	3 ´ 107 m/s
C.	3 ´ 108 m/s
D.	3 ´ 10-16 m/s
Answer» D. 3 ´ 10-16 m/s

Discussion

1934.	The rate of radiation of black body at 0°C is E watt. The rate of radiation of this black body at 273°C will be ?
A.	16 E
B.	8 E
C.	4 E
D.	E
Answer» B. 8 E

Discussion

1935.	The good absorber of heat are?
A.	Non-emitter
B.	Poor-emitter
C.	Good-emitter
D.	Highly polished
Answer» D. Highly polished

Discussion

1936.	A body cools from 50°C to 46°C in 5 minutes and to 40°C in the next 10 minutes. The surrounding temperature is ?
A.	30°C
B.	28°C
C.	36°C
D.	32°C
Answer» B. 28°C

Discussion

1937.	A black body is at a temperature of 500K. it emits energy at a rate which is proportional to ?
A.	500
B.	(500)2
C.	(500)3
D.	(500)4
Answer» E.

Discussion

1938.	A black body is at 300 K.it emits energy at a rate which is proportional to ?
A.	300
B.	(300)2
C.	(300)4
D.	(300)3
Answer» D. (300)3

Discussion

1939.	The earth receives its surface radiation from the sun at the rate of 1400 W/m2. The distance of the centre of the sun from the surface of the earth is 1.5 ´ 1011 m and the radius of the sun is 7.0 ´ 108 m. Treating sun as a black body, it follows from the above data that its surface temperature is?
A.	5801 K
B.	106 K
C.	50.1 K
D.	2801C
Answer» B. 106 K

Discussion

1940.	A body at high temperature T °K radiates heat at a rate proportional to?
A.	T4
B.	T3
C.	T
D.	T2
Answer» B. T3

Discussion

1941.	An object is at the temperature of 400°C. At what temperature would it radiant energy twice as first? The temperature of surrounding may be assumed to be negligible .
A.	200C
B.	200K
C.	800C
D.	800K
Answer» E.

Discussion

1942.	A cup of tea cools from 80°C to 60°C in one minute. The ambient temperature is 30°C in cooling from 60°C to 50°C, it will take?
A.	50 sec
B.	90 sec
C.	60 sec
D.	30 sec
Answer» B. 90 sec

Discussion

1943.	The temperature of a piece of metal is raised from 27°C to 51.2°C. The rate at which metal radiates energy increases nearly ?
A.	1.36 times
B.	2.36 times
C.	3.36 times
D.	4.36 times
Answer» B. 2.36 times

Discussion

1944.	A sphere, a cube and a thin circular plate, all made of the same material and having the same mass are initially heated to a temperature of 3000°K, which of these will cool fastest?
A.	Sphere
B.	Cube
C.	Plate
D.	None
Answer» D. None

Discussion

1945.	A metal piece heated to T1 °K. The temperature of the surrounding is T2°K.The heat in the surrounding due to radiation is proportional to ?
A.	T14 T24
B.	T1  T24
C.	T14  T24
D.	T13  T23
Answer» B. T1  T24

Discussion

1946.	If the temperature of the sun is doubled. The rate of energy received on the earth will be increased by a factor of?
A.	2
B.	4
C.	8
D.	16
Answer» E.

Discussion

1947.	A body in a room cools from 90°C to 80°C in 5 minutes. The time taken to cool from 70°C to 60°C is ?
A.	Less than 5 minute
B.	5 minute
C.	More than 5 minutes
D.	Less or more than 5 minutes depending upon the nature of the body
Answer» D. Less or more than 5 minutes depending upon the nature of the body

Discussion

1948.	The earth intercepts approximately one billionth of the power radiated by the sun. If the surface temperature of the sun were to drop by a factor of 2, the average radiant energy incident on earth per second would reduce by factor of ?
A.	2
B.	4
C.	8
D.	16
Answer» E.

Discussion

1949.	The best ideal black body is ?
A.	Lamp of charcoal heated to high temperature
B.	Metal coated with a black dye
C.	Glass surface coated with coalter
D.	Hollow enclosure blackened inside and having a small hole
Answer» E.

Discussion

1950.	Absorptive power of perfectly black body is ?
A.	Zero
B.	Infinity
C.	One
D.	Constant
Answer» D. Constant

Discussion

Explore topic-wise MCQs in General Knowledge.

Metals are good conductors of electricity because___.

Planets do not twinkle because___

Stars appears to move from east to west because____

Mirage is due to__

Nuclear sizes are expressed in a unit named?

Light year is a unit of?

Light from the Sun reaches us in nearly__.

The absorption of ink by blotting paper involves_____.

Large transformers, when used for some time, become very hot and are cooled by circulating oil. The heating of the transformer is due to____.

Siphon will fail to work if____.

It is easier to roll a stone up a sloping road than to lift it vertical upwards because__.

Wien’s constant units is?

Radiocarbon is produced in the atmosphere as a result of____

The unit of Stefan’s constant is?

A body at higher temperature T°K radiates heat at a rate which is proportional to ?

If a black body is heated from 27°C to 927°C. then the ratio of radiation emitted will be ?

A sphere cube and a thin circular plate all made of the same material and having the same mass are initially heated to a temperature of 300°C. Which of these cools fastest?

A black body emissive power is 81 J/m2 sec .It is at 300 K .Another one ordinary body emissivity is 0.8 it is at 500 K .then what is the emissive power of ordinary body?

Radiation emitted by a surface is directly proportional to ____.

Two spheres made of same material have radii in the ratio 2: 1. If both the spheres are at same temperature, then what is the ratio of heat radiation energy emitted per second by them?

A body cools from 100°C to 70°C in 8 minutes. If the room temperature is 15°C and assuming Newton’s law of cooling holds good, then time required for the body to cool from 70°C to 40°C is ?

Coefficient of transmission and coefficient of reflection for a given body are 0.22 and 0.74 respectively.Then, at a given temperature, the coefficient of emission for the body is ?

According to Prevost’s theory of heat exchange, the heat exchange shops at ?

Unit of Stefan’s constant is given by ?

The flow of heat from a hot body to a cold body is an example of?

For which of the following process, the thermal conduction is maximum?

A person with dark skin as compared to a person with white skin will experience ?

A perfectly black body emits radiation at temperature T1 K.If it is to radiate 16 times this power, its temperature T2 will be?

A black body at hot temperature at 227°C radiates heat at a rate of 5 cal/cm2 s. at a temperature of 727°C the rate of heat radiated per unit area will be?

In which process the rate of transfer of heat is maximum?

Two spheres made of same material have radii in the ratio 2:1. if both the spheres are at same temperature, then what is the ratio of heat radiation energy emitted per second by them?

A body cools from 60°C to 50°C in 10 minutes. If the room temperature is 25°C and assuming Newton’s law of cooling to hold good, the temperature of the body at the end of the next 10 minutes will be ?

The velocity with which thermal radiation travels in vacuum is?

The rate of radiation of black body at 0°C is E watt. The rate of radiation of this black body at 273°C will be ?

The good absorber of heat are?

A body cools from 50°C to 46°C in 5 minutes and to 40°C in the next 10 minutes. The surrounding temperature is ?

A black body is at a temperature of 500K. it emits energy at a rate which is proportional to ?

A black body is at 300 K.it emits energy at a rate which is proportional to ?

A body at high temperature T °K radiates heat at a rate proportional to?

An object is at the temperature of 400°C. At what temperature would it radiant energy twice as first? The temperature of surrounding may be assumed to be negligible .

A cup of tea cools from 80°C to 60°C in one minute. The ambient temperature is 30°C in cooling from 60°C to 50°C, it will take?

The temperature of a piece of metal is raised from 27°C to 51.2°C. The rate at which metal radiates energy increases nearly ?

A sphere, a cube and a thin circular plate, all made of the same material and having the same mass are initially heated to a temperature of 3000°K, which of these will cool fastest?

A metal piece heated to T1 °K. The temperature of the surrounding is T2°K.The heat in the surrounding due to radiation is proportional to ?

If the temperature of the sun is doubled. The rate of energy received on the earth will be increased by a factor of?

A body in a room cools from 90°C to 80°C in 5 minutes. The time taken to cool from 70°C to 60°C is ?

The earth intercepts approximately one billionth of the power radiated by the sun. If the surface temperature of the sun were to drop by a factor of 2, the average radiant energy incident on earth per second would reduce by factor of ?

The best ideal black body is ?

Absorptive power of perfectly black body is ?