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MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 3701. |
The value of Stefan?s constant is [RPMT 2002] |
| A. | \[5.67\times {{10}^{-8}}W/{{m}^{2}}\text{-}{{K}^{4}}\] |
| B. | \[5.67\times {{10}^{-5}}W/{{m}^{2}}\text{-}{{K}^{4}}\] |
| C. | \[5.67\times {{10}^{-11}}W/{{m}^{2}}\text{-}\,{{K}^{4}}\] |
| D. | None of these |
| Answer» B. \[5.67\times {{10}^{-5}}W/{{m}^{2}}\text{-}{{K}^{4}}\] | |
| 3702. |
An object is at a temperature of \[{{400}^{o}}C\]. At what temperature would it radiate energy twice as fast? The temperature of the surroundings may be assumed to be negligible [MP PMT 1990; DPMT 2002] |
| A. | \[{{200}^{o}}C\] |
| B. | \[200\ K\] |
| C. | \[{{800}^{o}}C\] |
| D. | 800 K |
| Answer» E. | |
| 3703. |
A sphere at temperature 600K is placed in an environment of temperature is 200K. Its cooling rate is H. If its temperature reduced to 400K then cooling rate in same environment will become [CBSE PMT 1999; BHU 2001] |
| A. | (3/16)H |
| B. | (16/3)H |
| C. | (9/27)H |
| D. | (1/16)H |
| Answer» B. (16/3)H | |
| 3704. |
The temperature of the body is increased from ?73 o C to 327 o C, the ratio of energy emitted per second is : [CPMT 2001; Pb. PET 2001] |
| A. | 1 : 3 |
| B. | 1 : 81 |
| C. | 1 : 27 |
| D. | 1 : 9 |
| Answer» C. 1 : 27 | |
| 3705. |
If the sun?s surface radiates heat at \[6.3\times {{10}^{7}}W{{m}^{-2}}\]. Calculate the temperature of the sun assuming it to be a black body \[(\sigma =5.7\times {{10}^{-8}}W{{m}^{-2}}{{K}^{-4}})\] [BHU (Med.) 2000] |
| A. | \[5.8\times {{10}^{3}}K\] |
| B. | \[8.5\times {{10}^{3}}K\] |
| C. | \[3.5\times {{10}^{8}}K\] |
| D. | \[5.3\times {{10}^{8}}K\] |
| Answer» B. \[8.5\times {{10}^{3}}K\] | |
| 3706. |
If the initial temperatures of metallic sphere and disc, of the same mass, radius and nature are equal, then the ratio of their rate of cooling in same environment will be [J & K CET 2004] |
| A. | 1 : 4 |
| B. | 4 : 1 |
| C. | 1 : 2 |
| D. | 2 : 1 |
| Answer» E. | |
| 3707. |
A black body radiates energy at the rate of 1 ´ 105 J / s ´m2 at temperature of 227o C. The temperature to which it must be heated so that it radiates energy at rate of 1 ´ 109J/sm2, is [DPMT 2004] |
| A. | 5000 K |
| B. | 5000 oC |
| C. | 500 K |
| D. | 500 oC |
| Answer» B. 5000 oC | |
| 3708. |
At 127o C radiates energy is 2.7 ´ 10-3 J/s. At what temperature radiated energy is 4.32 ´ 10 6 J/s [BCECE 2004] |
| A. | 400 K |
| B. | 4000 K |
| C. | 80000 K |
| D. | 40000 K |
| Answer» D. 40000 K | |
| 3709. |
Star A has radius r surface temperature T while star B has radius 4r and surface temperature T/2. The ratio of the power of two starts, PA : PB is [MP PMT 2004] |
| A. | 16 : 1 |
| B. | 1 : 16 |
| C. | 1 : 1 |
| D. | 1 : 4 |
| Answer» D. 1 : 4 | |
| 3710. |
Suppose the sun expands so that its radius becomes 100 times its present radius and its surface temperature becomes half of its present value. The total energy emitted by it then will increase by a factor of [AIIMS 2004] |
| A. | 104 |
| B. | 625 |
| C. | 256 |
| D. | 16 |
| Answer» C. 256 | |
| 3711. |
A black body radiates energy at the rate of \[E\] W/m2 at a high temperature TK. When the temperature is reduced to \[\frac{T}{2}K\], the radiant energy will be [CPMT 1988; UPSEAT 1998; MNR 1993; SCRA 1996; MP PMT 1992; DPMT 2001; MH CET 2001] |
| A. | \[\frac{E}{16}\] |
| B. | \[\frac{E}{4}\] |
| C. | \[4E\] |
| D. | \[16E\] |
| Answer» B. \[\frac{E}{4}\] | |
| 3712. |
The radiation emitted by a star A is 10,000 times that of the sun. If the surface temperatures of the sun and the star A are 6000 K and 2000 K respectively, the ratio of the radii of the star A and the sun is [EAMCET 2003] |
| A. | 300 : 1 |
| B. | 600 : 1 |
| C. | 900 : 1 |
| D. | 1200 : 1 |
| Answer» D. 1200 : 1 | |
| 3713. |
Two spheres of same material have radius 1m and 4 m and temperature 4000K and 2000K respectively. The energy radiated per second by the first sphere is [Pb. PMT 2002] |
| A. | Greater than that by the second |
| B. | Less than that by the second |
| C. | Equal in both cases |
| D. | The information is incomplete |
| Answer» D. The information is incomplete | |
| 3714. |
A black body radiates 20 W at temperature \[{{227}^{o}}C\]. If temperature of the black body is changed to \[{{727}^{o}}C\] then its radiating power will be [CBSE PMT 2002; DCE 1999, 03; AIIMS 2003] |
| A. | 120W |
| B. | 240 W |
| C. | 320 W |
| D. | 360 W |
| Answer» D. 360 W | |
| 3715. |
A black body at a temperature of 127°C radiates heat at the rate of 1 cal/cm2 ´ sec. At a temperature of 527°C the rate of heat radiation from the body in (cal/cm2 ´ sec) will be [MP PET 2002] |
| A. | 16.0 |
| B. | 10.45 |
| C. | 4.0 |
| D. | 2.0 |
| Answer» B. 10.45 | |
| 3716. |
Two identical metal balls at temperature \[{{200}^{o}}C\]and \[{{400}^{o}}C\] kept in air at \[{{27}^{o}}C\]. The ratio of net heat loss by these bodies is [CPMT 2002] |
| A. | 1/4 |
| B. | 1/2 |
| C. | 1/16 |
| D. | If temperature of surrounding is considered then net loss of energy of a body by radiation \[Q=A\varepsilon \sigma ({{T}^{4}}-T_{0}^{4})t\]Þ\[Q\propto ({{T}^{4}}-T_{0}^{4})\] Þ \[\frac{{{Q}_{1}}}{{{Q}_{2}}}=\frac{T_{1}^{4}-T_{0}^{4}}{T_{2}^{4}-T_{0}^{4}}\] \[=\frac{{{(273+200)}^{4}}-{{(273+27)}^{4}}}{{{(273+400)}^{4}}-{{(273+27)}^{4}}}\]\[=\frac{{{(473)}^{4}}-{{(300)}^{4}}}{{{(673)}^{4}}-{{(300)}^{4}}}\] |
| Answer» D. If temperature of surrounding is considered then net loss of energy of a body by radiation \[Q=A\varepsilon \sigma ({{T}^{4}}-T_{0}^{4})t\]Þ\[Q\propto ({{T}^{4}}-T_{0}^{4})\] Þ \[\frac{{{Q}_{1}}}{{{Q}_{2}}}=\frac{T_{1}^{4}-T_{0}^{4}}{T_{2}^{4}-T_{0}^{4}}\] \[=\frac{{{(273+200)}^{4}}-{{(273+27)}^{4}}}{{{(273+400)}^{4}}-{{(273+27)}^{4}}}\]\[=\frac{{{(473)}^{4}}-{{(300)}^{4}}}{{{(673)}^{4}}-{{(300)}^{4}}}\] | |
| 3717. |
If the temperature of a hot body is increased by 50% then the increase in the quantity of emitted heat radiation will be [RPET 1998; EAMCET 2001; MP PMT 2003] |
| A. | 125% |
| B. | 200% |
| C. | 300% |
| D. | 400% |
| Answer» E. | |
| 3718. |
A black body is at a temperature 300 K. It emits energy at a rate, which is proportional to [Pb. PMT 1998; AIIMS 2002; MH CET 2003] |
| A. | \[300\] |
| B. | \[{{(300)}^{2}}\] |
| C. | \[{{(300)}^{3}}\] |
| D. | \[{{(300)}^{4}}\] |
| Answer» E. | |
| 3719. |
The energy spectrum of a black body exhibits a maximum around a wavelength \[{{\lambda }_{o}}.\] The temperature of the black body is now changed such that the energy is maximum around a wavelength \[\frac{3{{\lambda }_{o}}}{4}\].The power radiated by the black body will now increase by a factor of [KCET 2002] |
| A. | 256/81 |
| B. | 64/27 |
| C. | 16/9 |
| D. | 4/3 |
| Answer» B. 64/27 | |
| 3720. |
The rate of radiation of a black body at 0°C is EJ/sec. The rate of radiation of this black body at \[{{273}^{o}}C\] will be [MP PMT 1989; Kerala PET 2002; UPSEAT 2001] |
| A. | \[16\ E\] |
| B. | \[{{T}_{2}}=8{{T}_{1}}\] |
| C. | \[4\ E\] |
| D. | \[E\] |
| Answer» B. \[{{T}_{2}}=8{{T}_{1}}\] | |
| 3721. |
Two black metallic spheres of radius 4m, at 2000 K and 1m at 4000 K will have ratio of energy radiation as [RPET 2000; AIEEE 2002] |
| A. | 1 : 1 |
| B. | 4 : 1 |
| C. | 1 : 4 |
| D. | 2 : 1 |
| Answer» B. 4 : 1 | |
| 3722. |
The original temperature of a black body is \[{{727}^{o}}C.\]The temperature at which this black body must be raised so as to double the total radiant energy, is [Pb. PMT 2001] |
| A. | 971 K |
| B. | 1190 K |
| C. | 2001 K |
| D. | 1458 K |
| Answer» C. 2001 K | |
| 3723. |
Temperature of a black body increases from \[{{327}^{o}}C\,\text{to}\,\text{92}{{\text{7}}^{\text{o}}}C\], the initial energy possessed is 2KJ, what is its final energy [DCE 2001] |
| A. | 32 KJ |
| B. | 320 KJ |
| C. | 1200 KJ |
| D. | None of these |
| Answer» B. 320 KJ | |
| 3724. |
At temperature T, the power radiated by a body is Q watts. At the temperature 3T the power radiated by it will be [MP PET 2000] |
| A. | 3 Q |
| B. | 9 Q |
| C. | 27 Q |
| D. | 81 Q |
| Answer» E. | |
| 3725. |
The rectangular surface of area 8 cm \[\times \] 4cm of a black body at a temperature of \[{{127}^{o}}C\] emits energy at the rate of E per second. If the length and breadth of the surface are each reduced to half of the initial value and the temperature is raised to \[{{327}^{o}}C\], the rate of emission of energy will become [MP PET 2000] |
| A. | \[\frac{3}{8}E\] |
| B. | \[\frac{81}{16}E\] |
| C. | \[\frac{9}{16}E\] |
| D. | \[\frac{81}{64}E\] |
| Answer» E. | |
| 3726. |
If the temperature of a black body be increased from \[{{27}^{o}}C\] to \[{{327}^{o}}C\] the radiation emitted increases by a fraction of [Pb. PET 1997; JIPMER 1999] |
| A. | 16 |
| B. | 8 |
| C. | 4 |
| D. | 2 |
| Answer» B. 8 | |
| 3727. |
The ratio of energy of emitted radiation of a black body at \[{{27}^{o}}C\] and \[{{927}^{o}}C\] is [Pb. PMT 1995; CPMT 1997, 2000; CBSE PMT 2000; DPMT 1998, 02, 03] |
| A. | 1 : 4 |
| B. | 1 : 16 |
| C. | 1 : 64 |
| D. | 1 : 256 |
| Answer» E. | |
| 3728. |
A spherical black body with a radius of \[12\ cm\] radiates \[440\ W\] power at \[500\ K\]. If the radius were halved and the temperature doubled, the power radiated in watt would be [IIT 1997 Re-Exam] |
| A. | 225 |
| B. | 450 |
| C. | 900 |
| D. | 1800 |
| Answer» E. | |
| 3729. |
A metal ball of surface area \[200\ c{{m}^{2}}\] and temperature \[{{527}^{o}}C\] is surrounded by a vessel at \[{{27}^{o}}C\]. If the emissivity of the metal is 0.4, then the rate of loss of heat from the ball is \[(\sigma =5.67\times {{10}^{-8}}J/{{m}^{2}}\ -s-{{k}^{4}})\] [MP PMT/PET 1988] |
| A. | 108 joules approx. |
| B. | 168 joules approx. |
| C. | 182 joules approx. |
| D. | 192 joules approx. |
| Answer» D. 192 joules approx. | |
| 3730. |
The radiant energy from the sun incident normally at the surface of earth is \[20\ kcal/{{m}^{2}}min\]. What would have been the radiant energy incident normally on the earth, if the sun had a temperature twice of the present one [CBSE PMT 1998; Pb. PET 2001] |
| A. | \[160\ kcal/{{m}^{2}}\ min\] |
| B. | \[40\ kcal/{{m}^{2}}\ min\] |
| C. | \[320\ kcal/{{m}^{2}}\ min\] |
| D. | \[80\ kcal/{{m}^{2}}\ min\] |
| Answer» D. \[80\ kcal/{{m}^{2}}\ min\] | |
| 3731. |
The temperatures of two bodies \[A\] and \[B\] are respectively \[{{727}^{o}}C\] and \[{{327}^{o}}C\]. The ratio \[{{H}_{A}}:{{H}_{B}}\] of the rates of heat radiated by them is [UPSEAT 1999; MP PET 1999; MH CET 2000; AIIMS 2000] |
| A. | \[727:327\] |
| B. | 5 : 3 |
| C. | 25 : 9 |
| D. | 625 : 81 |
| Answer» E. | |
| 3732. |
A thin square steel plate with each side equal to 10 cm is heated by a blacksmith. The rate of radiated energy by the heated plate is 1134 W. The temperature of the hot steel plate is (Stefan's constant \[\sigma =5.67\times {{10}^{-8}}watt\ {{m}^{-2}}{{K}^{-4}}\], emissivity of the plate = 1) [MP PMT 1995] |
| A. | \[1000\ K\] |
| B. | \[1189\ K\] |
| C. | \[2000\ K\] |
| D. | \[2378\ K\] |
| Answer» C. \[2000\ K\] | |
| 3733. |
A body radiates energy \[5W\] at a temperature of \[{{127}^{o}}C\]. If the temperature is increased to \[{{927}^{o}}C\], then it radiates energy at the rate of [MP PET 1994;BHU 1995; CPMT 1998; AFMC 2000] |
| A. | \[410W\] |
| B. | \[81\ W\] |
| C. | \[405\ W\] |
| D. | \[200\ W\] |
| Answer» D. \[200\ W\] | |
| 3734. |
Two spheres \[P\] and \[Q\], of same colour having radii \[8\ cm\] and \[2\ cm\] are maintained at temperatures \[{{127}^{o}}C\] and \[{{527}^{o}}C\] respectively. The ratio of energy radiated by \[P\] and \[Q\] is [MP PMT 1994] |
| A. | 0.054 |
| B. | 0.0034 |
| C. | 1 |
| D. | 2 |
| Answer» D. 2 | |
| 3735. |
The temperature at which a black body of unit area loses its energy at the rate of 1 joule/second is |
| A. | \[-{{65}^{o}}C\] |
| B. | \[{{65}^{o}}C\] |
| C. | 65 K |
| D. | None of these |
| Answer» D. None of these | |
| 3736. |
The temperatures of two bodies A and B are \[{{727}^{o}}C\] and \[{{127}^{o}}C\]. The ratio of rate of emission of radiations will be [MP PET 1986] |
| A. | 727/127 |
| B. | 625/16 |
| C. | 1000/400 |
| D. | 100/16 |
| Answer» C. 1000/400 | |
| 3737. |
The temperature of a piece of iron is \[{{27}^{o}}C\] and it is radiating energy at the rate of \[Q\ kW{{m}^{-2}}\]. If its temperature is raised to \[{{151}^{o}}C\], the rate of radiation of energy will become approximately [MP PET 1992] |
| A. | \[2Q\ kW{{m}^{-2}}\] |
| B. | \[4Q\ kW{{m}^{-2}}\] |
| C. | \[6Q\ kW{{m}^{-2}}\] |
| D. | \[8Q\ kW{{m}^{-2}}\] |
| Answer» C. \[6Q\ kW{{m}^{-2}}\] | |
| 3738. |
Liquid is filled in a vessel which is kept in a room with temperature \[{{20}^{o}}C\]. When the temperature of the liquid is \[{{80}^{o}}C\], then it loses heat at the rate of \[60\ cal/\sec \]. What will be the rate of loss of heat when the temperature of the liquid is \[{{40}^{o}}C\] [MP PMT 1994] |
| A. | \[180\ cal/\sec \] |
| B. | \[40\ cal/\sec \] |
| C. | \[30\ cal/\sec \] |
| D. | \[20\ cal/\sec \] |
| Answer» E. | |
| 3739. |
A body cools from \[{{60}^{o}}C\] to \[{{50}^{o}}C\] in 10 minutes when kept in air at \[{{30}^{o}}C\]. In the next 10 minutes its temperature will be [MP PET 1994] |
| A. | Below \[{{40}^{o}}C\] |
| B. | \[{{40}^{o}}C\] |
| C. | Above \[{{40}^{o}}C\] |
| D. | Cannot be predicted |
| Answer» D. Cannot be predicted | |
| 3740. |
Newton's law of cooling is used in laboratory for the determination of the [CPMT 1973; CPMT 2002] |
| A. | Specific heat of the gases |
| B. | The latent heat of gases |
| C. | Specific heat of liquids |
| D. | Latent heat of liquids |
| Answer» D. Latent heat of liquids | |
| 3741. |
Equal masses of two liquids are filled in two similar calorimeters. The rate of cooling will [MP PMT 1987] |
| A. | Depend on the nature of the liquids |
| B. | Depend on the specific heats of liquids |
| C. | Be same for both the liquids |
| D. | Depend on the mass of the liquids |
| Answer» C. Be same for both the liquids | |
| 3742. |
Newton's law of cooling is a special case of |
| A. | Stefan's law |
| B. | Kirchhoff's law |
| C. | Wien's law |
| D. | Planck's law |
| Answer» B. Kirchhoff's law | |
| 3743. |
A cane is taken out from a refrigerator at 0°C. The atmospheric temperature is 25°C. If t1 is the time taken to heat from 0°C to 5°C and t2 is the time taken from 10°C to 15°C, then [Orissa JEE 2005] |
| A. | \[{{t}_{1}}>{{t}_{2}}\] |
| B. | \[{{t}_{1}}<{{t}_{2}}\] |
| C. | \[{{t}_{1}}={{t}_{2}}\] |
| D. | There is no relation |
| Answer» C. \[{{t}_{1}}={{t}_{2}}\] | |
| 3744. |
An object is cooled from 75°C to 65°C in 2 minutes in a room at 30°C. The time taken to cool another object from 55°C to 45°C in the same room in minutes is [EAMCET (Med.) 1996] |
| A. | 4 |
| B. | 5 |
| C. | 6 |
| D. | 7 |
| Answer» B. 5 | |
| 3745. |
A body takes 5 minute to cool from 80°C to 50°C. How much time it will take to cool from 60°C to 30°C, if room temperature is 20°C. [RPET 1998] |
| A. | 40 minute |
| B. | 9 minute |
| C. | 30 minute |
| D. | 20 minute |
| Answer» C. 30 minute | |
| 3746. |
A body takes 5 minutes to cool from 90oC to 60oC. If the temperature of the surroundings is 20oC, the time taken by it to cool from 60oC to 30oC will be. [RPMT 2003] |
| A. | 5 min |
| B. | 8 min |
| C. | 11 min |
| D. | 12 min |
| Answer» D. 12 min | |
| 3747. |
The temperature of a body falls from 62oC to 50oC in 10 minutes. If the temperature of the surroundings is 26oC, the temperature in next 10 minutes will become [RPMT 2002] |
| A. | 42oC |
| B. | 40oC |
| C. | 56oC |
| D. | 55oC |
| Answer» B. 40oC | |
| 3748. |
A cup of tea cools from 65.5o C to 62.5 o C in one minute in a room of 22.5 o C. How long will the same cup of tea take, in.............. minutes, to cool from 46.50 o C to 40.5 o C in the same room ? (choose nearest value) [Kerala PMT 2004] |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» E. | |
| 3749. |
The initial temperature of a body is 80°C. If its temperature falls to 64°C in 5 minutes and in 10 minutes to 52°C then the temperature of surrounding will be [MP PMT 2003] |
| A. | 26°C |
| B. | 49°C |
| C. | 35°C |
| D. | 42°C |
| Answer» C. 35°C | |
| 3750. |
Consider two hot bodies \[{{B}_{1}}\] and \[{{B}_{2}}\] which have temperatures \[{{100}^{o}}C\] and \[{{80}^{o}}C\] respectively at \[t=0\]. The temperature of the surroundings is \[{{40}^{o}}C\]. The ratio of the respective rates of cooling \[{{R}_{1}}\] and \[{{R}_{2}}\] of these two bodies at \[t=0\] will be [MP PET 1990] |
| A. | \[{{R}_{1}}:{{R}_{2}}=3:2\] |
| B. | \[{{R}_{1}}:{{R}_{2}}=5:4\] |
| C. | \[{{R}_{1}}:{{R}_{2}}=2:3\] |
| D. | \[{{R}_{1}}:{{R}_{2}}=4:5\] |
| Answer» B. \[{{R}_{1}}:{{R}_{2}}=5:4\] | |