A hot body will radiate heat most rapidly, if its surface is (A) White & rough (B) Black & rough (C) White & polished (D) Black & polished

A hot body will radiate heat most rapidly, if its surface is

(A) White & rough

(B) Black & rough

(C) White & polished

(D) Black & polished

by

1 Answer

Answer :

(B) Black & rough

by

Related questions

A __________ surface has the maximum thermal emissivity out of the following. (A) Black & smooth (B) Black & rough (C) White & smooth (D) White & rough

Description : A __________ surface has the maximum thermal emissivity out of the following. (A) Black & smooth (B) Black & rough (C) White & smooth (D) White & rough

Last Answer : (B) Black & rough

Nucleate boiling is promoted (A) On polished surfaces (B) On rough surfaces (C) In the absence of agitation (D) None of these

Description : Nucleate boiling is promoted (A) On polished surfaces (B) On rough surfaces (C) In the absence of agitation (D) None of these

Last Answer : (B) On rough surfaces

A body absorbs heat most if it is – (1) black and rough (2) black and smooth (3) white and rough (4) white and smooth

Description : A body absorbs heat most if it is – (1) black and rough (2) black and smooth (3) white and rough (4) white and smooth

Last Answer : (1) black and rough Explanation: A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. Another property is roughness. Sand is rough and black and so it is a good absorber.

A body absorbs heat most if it is (1) black and rough (2) black and smooth (3) white and rough (4) white and smooth

Description : A body absorbs heat most if it is (1) black and rough (2) black and smooth (3) white and rough (4) white and smooth

Last Answer : black and rough

When will a hot body radiate maximum energy? -General Knowledge

Description : When will a hot body radiate maximum energy? -General Knowledge

Last Answer : answer:

When will a hot body radiate maximum energy? -General Knowledge

Description : When will a hot body radiate maximum energy? -General Knowledge

Last Answer : answer:

When will a hot body radiate maximum energy?

Description : When will a hot body radiate maximum energy?

Last Answer : If its surface is black and rough

The main reason for making the copper calorimeter (used in bomb calorimeter) silvery white and shining/polished is to (A) Minimise its corrosion (B) Avoid radiation heat loss (C) Make it look attractive (D) None of these

Description : The main reason for making the copper calorimeter (used in bomb calorimeter) silvery white and shining/polished is to (A) Minimise its corrosion (B) Avoid radiation heat loss (C) Make it look attractive (D) None of these

Last Answer : (B) Avoid radiation heat loss

Hot coffee is poured simultaneously in four metallic tumblers painted outside with different types of paints. After some time, the coffee will be found coldest in the tumbler painted (a) rough white (b) shining white (c) rough black (d) shining black

Description : Hot coffee is poured simultaneously in four metallic tumblers painted outside with different types of paints. After some time, the coffee will be found coldest in the tumbler painted (a) rough white (b) shining white (c) rough black (d) shining black

Last Answer : Ans:(c)

The most conducive surface for dropwise condensation to occur is the __________ surface. (A) Coated (B) Oily (C) Glazed & polished (D) Smooth

Description : The most conducive surface for dropwise condensation to occur is the __________ surface. (A) Coated (B) Oily (C) Glazed & polished (D) Smooth

Last Answer : (B) Oily

The thermal radiation emitted by a body is proportional to T n , where T is its absolute temperature. The value of 'n' is exactly 4 for (A) Black painted bodies only (B) All bodies (C) Polished bodies only (D) A black body

Description : The thermal radiation emitted by a body is proportional to T n , where T is its absolute temperature. The value of 'n' is exactly 4 for (A) Black painted bodies only (B) All bodies (C) Polished bodies only (D) A black body

Last Answer : (B) All bodies

Clothes keep us warm in winter because they : (1) supply heat (2) do not radiate heat (3) prevent air from contacting the body (4) prevent the heat of the body from escaping

Description : Clothes keep us warm in winter because they : (1) supply heat (2) do not radiate heat (3) prevent air from contacting the body (4) prevent the heat of the body from escaping

Last Answer : (4) prevent the heat of the body from escaping Explanation: It is just because woolen clothes have fibres and between those fibres air is trapped which reduces heat loss. Air reduces heat loss ... heat from our body gets trapped inside the clothes which makes us feels warmer with the clothes.

At what temperature a body will not radiate any heat energy? (1) 0° C (2) 273° C (3) 100° C (4) -273° C

Description : At what temperature a body will not radiate any heat energy? (1) 0° C (2) 273° C (3) 100° C (4) -273° C

Last Answer : (4) -273° C

Clothes keep us warm in winter because they : (1) supply heat (2) do not radiate heat (3) prevent air from contacting the body (4) prevent the heat of the body from escaping

Description : Clothes keep us warm in winter because they : (1) supply heat (2) do not radiate heat (3) prevent air from contacting the body (4) prevent the heat of the body from escaping

Last Answer : prevent the heat of the body from escaping

Cloudy nights are wanner compared nights, because clouds mainly – (1) Absorb heat from the atmosphere send it towards earth (2) Prevent cold waves from the sky descending on earth (3) Reflect back the heat given by earth (4) Produce heat and radiate it toward earth

Description : Cloudy nights are wanner compared nights, because clouds mainly – (1) Absorb heat from the atmosphere send it towards earth (2) Prevent cold waves from the sky descending on earth (3) Reflect back the heat given by earth (4) Produce heat and radiate it toward earth

Last Answer : (3) Reflect back the heat given by earth Explanation: It is because the night side of Earth will radiate infra-red radiation (heat) back into space. When there is cloud cover, the clouds act like a blanket and trap the heat close to the ground just like a blanket traps heat close to our body.

The cloudy nights are warmer compared to clear nights (without clouds) during winter days. This is because: (A) clouds radiate heat towards the earth (B) clouds prevent cold wave from the sky, descend on earth (C) clouds prevent escaping of the heat radiation from the earth (D) clouds being at great heights from earth absorb heat from the sun and send towards the earth

Description : The cloudy nights are warmer compared to clear nights (without clouds) during winter days. This is because: (A) clouds radiate heat towards the earth (B) clouds prevent cold wave from the sky, ... (D) clouds being at great heights from earth absorb heat from the sun and send towards the earth

Last Answer : (C) clouds prevent escaping of the heat radiation from the earth

Cloudy nights are warmer compared nights, because clouds mainly (1) absorb heat from the atmosphere send it towards earth (2) prevent cold waves from the sky descending on earth (3) reflect back the heat given by earth (4) produce heat and radiate it toward earth

Description : Cloudy nights are warmer compared nights, because clouds mainly (1) absorb heat from the atmosphere send it towards earth (2) prevent cold waves from the sky descending on earth (3) reflect back the heat given by earth (4) produce heat and radiate it toward earth

Last Answer : reflect back the heat given by earth

Pick out the wrong statement. (A) The emissivity of a surface decreases, if it gets corroded by atmospheric environment (B) The emissivity of a surface increases with increase in surface roughness (C) The emissivity of a polished surface is quite low (D) The emissivity of a non-metallic surface decreases with increase in the temperature

Description : Pick out the wrong statement. (A) The emissivity of a surface decreases, if it gets corroded by atmospheric environment (B) The emissivity of a surface increases with increase in surface roughness ... quite low (D) The emissivity of a non-metallic surface decreases with increase in the temperature

Last Answer : (A) The emissivity of a surface decreases, if it gets corroded by atmospheric environment

The water in an open pond remains cool even in hot summer because (a) Of continuous evaporation of water (b) Water radiates heat more rapidly than the atmosphere (c) Water absorbs heat less rapidly than the atmosphere (d) Water absorbs heat more rapidly than the atmosphere

Description : The water in an open pond remains cool even in hot summer because (a) Of continuous evaporation of water (b) Water radiates heat more rapidly than the atmosphere (c) Water absorbs heat less rapidly than the atmosphere (d) Water absorbs heat more rapidly than the atmosphere

Last Answer : Ans:(c)

Which of the following is not a characteristic observed in material failure by fatigue fracture? (A) Plastic deformation of material does not occur (B) Initiation of crack from below the surface does not occur (C) Initiation of crack occurs on the surface of the machine part (D) Presence of both rough & smooth zone with conchoidal markings in smooth zone of the surface

Description : Which of the following is not a characteristic observed in material failure by fatigue fracture? (A) Plastic deformation of material does not occur (B) Initiation of crack from below the surface does ... (D) Presence of both rough & smooth zone with conchoidal markings in smooth zone of the surface

Last Answer : Option B

Infrared rays are absorbed best by which one of the following. Is it: w) bodies of air x) white bodies with rough surfaces y) mirrors z) black bodies with rough surfaces

Description : Infrared rays are absorbed best by which one of the following. Is it: w) bodies of air x) white bodies with rough surfaces y) mirrors z) black bodies with rough surfaces

Last Answer : ANSWER: Z -- BLACK BODIES WITH ROUGH SURFACES

Copper is often used as an electrical conductor because it _______________. A. has high resistance at low temperatures B. has a highly polished surface C. is able to pass current with little opposition D. holds insulation together well

Description : Copper is often used as an electrical conductor because it _______________. A. has high resistance at low temperatures B. has a highly polished surface C. is able to pass current with little opposition D. holds insulation together well

Last Answer : Answer: C

Why rate of condensation is higher on a polished surface compared to rusty surface ?

Description : Why rate of condensation is higher on a polished surface compared to rusty surface ?

Last Answer : Polished surface promotes drop wise condensation and does not wet the surface.

How do you reduce the loss that is produced when light strikes a flat polished end of a fiber optic? A. By painting the surface B. By inclining the surface C. By cooling D. By application of antireflection coating

Description : How do you reduce the loss that is produced when light strikes a flat polished end of a fiber optic? A. By painting the surface B. By inclining the surface C. By cooling D. By application of antireflection coating

Last Answer : D. By application of antireflection coating

Which is NOT a characteristic of emissivity?  A. It is high with most nonmetals  B. It is directly proportional to temperature  C. It is independent with the surface condition of the material  D. It is low with highly polished metals

Description : Which is NOT a characteristic of emissivity?  A. It is high with most nonmetals  B. It is directly proportional to temperature  C. It is independent with the surface condition of the material  D. It is low with highly polished metals

Last Answer : It is independent with the surface condition of the material

The base of an electric iron is brightly polished mainly - (1) to make it smooth and frictionless (2) to make it rust-proof (3) to reduce heat loss by radiation (4) to make it more durable

Description : The base of an electric iron is brightly polished mainly - (1) to make it smooth and frictionless (2) to make it rust-proof (3) to reduce heat loss by radiation (4) to make it more durable

Last Answer : (3) to reduce heat loss by radiation Explanation: Polished surfaces are poor radiators of heat. So loss of heat on that account is reduced and the electric iron remains hotter than otherwise.

The base of an electric iron is brightly polished mainly - (1) to make it smooth and frictionless (2) to make it rust-proof (3) to reduce heat loss by radiation (4) to make it more durable

Description : The base of an electric iron is brightly polished mainly - (1) to make it smooth and frictionless (2) to make it rust-proof (3) to reduce heat loss by radiation (4) to make it more durable

Last Answer : (3) to reduce heat loss by radiation Explanation: Polished surfaces are poor radiators of heat. So loss of heat on that account is reduced and the electric iron remains hotter than otherwise.

Which of the following parameters is not responsible for the heat loss from a hot steam carrying bare pipe surface located in a room without fans? (A) Emissivity of pipe surface (B) Diameter & length of the pipe (C) Temperature of hot pipe surface & that of air in the room (D) None of thes

Description : Which of the following parameters is not responsible for the heat loss from a hot steam carrying bare pipe surface located in a room without fans? (A) Emissivity of pipe surface (B) Diameter & length of the pipe (C) Temperature of hot pipe surface & that of air in the room (D) None of thes

Last Answer : Option D

Consider the following statements regarding Coulomb’s theory of earth pressure: 1. It is based on wedge theory of earth pressure. 2. It assumes the wall surface to be rough. 3. It may or may not satisfy the static equilibrium condition occurring in nature. Which of these statements are correct? (a) 1, 2 & 3 (b) 1 & 2 only (c) 2 & 3 only (d) 1 & 3 only

Description : Consider the following statements regarding Coulomb's theory of earth pressure: 1. It is based on wedge theory of earth pressure. 2. It assumes the wall surface to be rough. 3. It may or may not satisfy the static equilibrium condition ... 1, 2 & 3 (b) 1 & 2 only (c) 2 & 3 only (d) 1 & 3 only

Last Answer : (b) 1 & 2 only

The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by (A) Painting the surface black (B) Painting the surface white (with aluminium paint) (C) Giving the surface a mirror finish (D) Roughening the surface

Description : The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by (A) Painting the surface black (B) ... white (with aluminium paint) (C) Giving the surface a mirror finish (D) Roughening the surface

Last Answer : (B) Painting the surface white (with aluminium paint)

A black body when hot, emits heat radiation of __________ wavelengths. (A) Small (B) Large (C) All (D) One fixed

Description : A black body when hot, emits heat radiation of __________ wavelengths. (A) Small (B) Large (C) All (D) One fixed

Last Answer : (C) All

A body of mass 37 kg rests on a rough horizontal surface. The minimum horizontal force required to just start the motion

Description : A body of mass 37 kg rests on a rough horizontal surface. The minimum horizontal force required to just start the motion

Last Answer : A body of mass 37 kg rests on a rough horizontal surface. The minimum horizontal force required to just start the ... ) µs = 0.188 b) µk = 0.118

In the equation of virtual work, following force is neglected (A) Reaction of any smooth surface with which the body is in contact (B) Reaction of a rough surface of a body which rolls on it without slipping (C) Reaction at a point or an axis, fixed in space, around which a body is constrained to turn (D) All of the above

Description : In the equation of virtual work, following force is neglected (A) Reaction of any smooth surface with which the body is in contact (B) Reaction of a rough surface of a body which rolls on it without ... an axis, fixed in space, around which a body is constrained to turn (D) All of the above

Last Answer : (D) All of the above

Consider the following four conditions (1 - 4) and select a correct pair of them as adaptations to environment in desert lizards. Conditions: 1. Burrowing in soil to escape high temperature. 2. Losing heat rapidly from the body during high temperature. 3. Bask in sun when temperature is low. 4. Insulating body due to thick fatty dermis. (a) 3, 4 (b) 1, 3 (c) 2, 4 (d) 1, 2

Description : Consider the following four conditions (1 - 4) and select a correct pair of them as adaptations to environment in desert lizards. Conditions: 1. Burrowing in soil to escape high temperature. 2. Losing heat rapidly from the body during ... to thick fatty dermis. (a) 3, 4 (b) 1, 3 (c) 2, 4 (d) 1, 2

Last Answer : (b) 1, 3

Why does ETA radiate so much terror?

Description : Why does ETA radiate so much terror?

Last Answer : Because they’re basically terrorists, and rather prolific ones at that? Like any other group like that some view them as freedom fighters, some view them as terrorists.

where does the kidney hurt, where does the pain radiate?

Description : Where exactly does the kidney hurt? Can he believe that only a man's waist hurts? 

Last Answer : To my knowledge, kidney pain occurs above the buttocks and around the spine on 2 sides of the spine. It's easy to confuse it with other low back pain, but if you have something with your kidneys ... pain usually occurs as a result of movement, and kidney pain also occurs by tapping the waist.   

Does a lighted mouse radiate?

Description : We have a new mouse at home on a PC that glows red and in the evening it lights up half the room. Can't the light from the mouse radiate something when used in the body?

Last Answer : I have been working on a PC for several years and my hands are working. And I have a damn very luminous rat.

A disadvantage of using a trap antenna. A. It will radiate harmonics B. It can only be used for single-bad operation C. It is too sharply directional at lower frequencies D. It must be neutralized

Description : A disadvantage of using a trap antenna. A. It will radiate harmonics B. It can only be used for single-bad operation C. It is too sharply directional at lower frequencies D. It must be neutralized

Last Answer : A. It will radiate harmonics

To radiate power efficiently, a long-wire antenna must have what minimum overall length?

Description : To radiate power efficiently, a long-wire antenna must have what minimum overall length?

Last Answer : One-half wavelength.

The fields surrounding the antenna do not collapse their energy back into the antenna but rather radiate it out in space

Description : The fields surrounding the antenna do not collapse their energy back into the antenna but rather radiate it out in space

Last Answer : radiation field

Short-circuited stubs are preferred to open-circuited stubs because thelatter are a. more difficult to make an connect b. made of a transmission line with a different characteristic impedance c. liable to radiate

Description : Short-circuited stubs are preferred to open-circuited stubs because thelatter are a. more difficult to make an connect b. made of a transmission line with a different characteristic impedance c. liable to radiate

Last Answer : c. liable to radiate

Choose the most appropriate statement (A) An antenna can radiate only HF signals

Description : Choose the most appropriate statement (A) An antenna can radiate only HF signals (B) An antenna can radiate and receive HF signals (C) An antenna can receive only HF signals (D) An antenna can receive and transmit simultaneously HF signals

Last Answer : Choose the most appropriate statement (A) An antenna can radiate only HF signals (B) An antenna can radiate and receive HF signals (C) An antenna can receive only HF signals (D) An antenna can receive and transmit simultaneously HF signals

Dropwise condensation occurs on __________ surfaces. (A) Clean and dirt free (B) Smooth clean (C) Contaminated cooling (D) Polished

Description : Dropwise condensation occurs on __________ surfaces. (A) Clean and dirt free (B) Smooth clean (C) Contaminated cooling (D) Polished

Last Answer : (C) Contaminated cooling

A black surface absorbs more heat radiations as compared to a white or a reflecting surface under identical conditions. List two solar devices which make use of this property in their design. -Science

Description : A black surface absorbs more heat radiations as compared to a white or a reflecting surface under identical conditions. List two solar devices which make use of this property in their design. -Science

Last Answer : Solar cooker, solar water heater.

During hot weather, the fan produces a feeling of comfort. This is because – (1) fan supplies cool air (2) fan cools the air (3) our perspiration evaporates rapidly (4) conductivity of air increases

Description : During hot weather, the fan produces a feeling of comfort. This is because – (1) fan supplies cool air (2) fan cools the air (3) our perspiration evaporates rapidly (4) conductivity of air increases

Last Answer : (3) our perspiration evaporates rapidly Explanation: Fans make the air more comfortable for two reasons: (1) by moving the air, they blow away body heat and evaporate sweat, cooling the body, and (2) they also mix the cooler air near the floor with the warmer air by people's faces.

During hot weather, the fan produces a feeling of comfort. This is because (1) fan supplies cool air (2) fan cools the air (3) our perspiration eva-porates rapidly (4) conductivity of air increases

Description : During hot weather, the fan produces a feeling of comfort. This is because (1) fan supplies cool air (2) fan cools the air (3) our perspiration eva-porates rapidly (4) conductivity of air increases 

Last Answer : our perspiration eva-porates rapidly

In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness. Two pipes are said to have the same hydraulic roughness, when they have equal values of (A) Relative roughness (B) Absolute roughness (C) Friction co-efficient for flows at equal Reynold number (D) All (A), (B) & (C)

Description : In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness. Two pipes are said ... co-efficient for flows at equal Reynold number (D) All (A), (B) & (C)

Last Answer : (C) Friction co-efficient for flows at equal Reynold number

Consider two pipes of same length and diameter through which water is passed at the same velocity. The friction factor for rough pipe is f1 and that for smooth pipe is f2 . Pick out the correct statement(A) f1 = f2 (B) f1 < f2 (C) f1 > f2 (D) Data not sufficient to relate f1 & f2

Description : Consider two pipes of same length and diameter through which water is passed at the same velocity. The friction factor for rough pipe is f1 and that for smooth pipe is f2 . Pick out the correct statement. (A) f1 = f2 (B) f1 < f2 (C) f1 > f2 (D) Data not sufficient to relate f1 & f2

Last Answer : (C) f1 > f2

The term dispersion describes the process of ∙ A. separating light into its component frequencies ∙ B. reflecting light from a smooth surface ∙ C. the process by which light is absorbed by an uneven rough surface ∙ D. light scattering

Description : The term dispersion describes the process of ∙ A. separating light into its component frequencies ∙ B. reflecting light from a smooth surface ∙ C. the process by which light is absorbed by an uneven rough surface ∙ D. light scattering

Last Answer : A. separating light into its component frequencies