Physics - Thermal Properties Matter - Quiz-8

The two ends of a metal rod are maintained at temperatures 100 °C and 110 °C. The rate of heat flow in the rod is found to be 4.0 J/s. If the ends are maintained at temperatures 200 °C and 210 °C, the rate of heat flow will be:

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44.0 J/s
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16.8 J/s
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8.0 J/s
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4.0 J/s

Liquid oxygen at 50 K is heated up to 300 K at a constant pressure of 1 atm. The rate of heating is constant. Which one of the following graphs represents the variation of temperature with time?

The freezer in a refrigerator is located at the top section so that

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the entire chamber of the refrigerator is cooled quickly due to convection
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the motor is not heated
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the heat gained from the environment is high
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the heat gained from the environment is low

Assertion: It is hotter over the top of a fire than at the same distance of the side.
Reason: Air surrounding the fire conducts, more heat upward.

If both the assertion and the reason are true and the reason is a correct explanation of the assertion
If both the assertion and reason are true but the reason is not a correct explanation of the assertion
If the assertion is true but the reason is false
If both the assertion and reason are false

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1
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2
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3
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4

In a new temperature scale, freezing point of water is given a value $10 x$ and boiling point of water is $90 x$ . Reading of new temperature scale for a temperature equal to $10 ° C$ is

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$14 x$
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$16 x$
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$18 x$
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$12 x$

The temperature of a body on the Kelvin scale is found to be x K. When it is measured by a Fahrenheit thermometer, it is found to be x $°$ F, then the value of x is:

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40
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313
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574.25
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301.25

A black body at 227 °C radiates heat at the rate of 7 cal-cm^-2s^-1. At a temperature of 727 °C, the rate of heat radiated in the same units will be:

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60
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50
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112
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80

The two ends of a rod of length L and a uniform cross-sectional area A are kept at two temperatures T₁ and T₂ (T₁> T₂). The rate of heat transfer

\frac{dQ}{dt}

through the rod in steady state is given by:

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$\frac{dQ}{dt} = \frac{KL (T_{1} - T_{2})}{A}$
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$\frac{dQ}{dt} = \frac{K (T_{1} - T_{2})}{LA}$
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$\frac{dQ}{dt} = KLA (T_{1} - T_{2})$
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$\frac{dQ}{dt} = \frac{KA (T_{1} - T_{2})}{L}$

If the cold junction of a thermocouple is kept at 0 °C and the hot junction is kept at T °C, then the relation between neutral temperature ( $T_{n}$ ) and temperature of inversion ( $T_{i}$ ) is:

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$T_{n} = \frac{T_{i}}{2}$
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$T_{n}$ = 2 $T_{i}$
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$T_{n}$ = $T_{i}$ - T
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$T_{n}$ = $T_{i}$ + T

Assuming the sun to have a spherical outer surface of radius r, radiating like a black body at temperature t °C, the power received by a unit surface of the earth (normal to the incident rays) at a distance R from the centre of the sun is:
(where σ is Stefan’s constant.)

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$\frac{4 {πr}^{2} {σt}^{4}}{R^{2}}$
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$\frac{r^{2} σ (t + 273)^{4}}{4 π R^{2}}$
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$\frac{16 π^{2} r^{2} {σt}^{4}}{R^{2}}$
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4 $\frac{r^{2} σ (t + 273)^{4}}{R^{2}}$

A black body is at 727 °C. It emits energy at a rate that is proportional to:

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$(727)^{2}$
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$(1000)^{4}$
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$(1000)^{2}$
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$(727)^{4}$

A black body at 1227 °C emits radiations with maximum intensity at a wavelength of 5000 Å. If the temperature of the body is increased by 1000 °C, the maximum intensity will be observed at:

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4000 Å
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5000 Å
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6000 Å
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3000 Å

A copper rod of 88 cm and an aluminium rod of an unknown length have an equal increase in their lengths independent of an increase in temperature. The length of the aluminium rod is : $(α_{C u} = 1.7 \times 10^{- 5} K^{- 1} a n d$ $α_{A l} = 2.2 \times 10^{- 5} K^{- 1})$

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68 cm
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6.8 cm
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113.9 cm
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88 cm

In which of the following phenomenon heat convection does not take place

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land and sea breeze
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boiling of water
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heating of glass surface due to filament of the bulb
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air around the furnace

The graph AB shown in figure is a plot of
temperature of a body in degree Celsius and
degree Fahrenheit. Then

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slope of line AB is 9/5
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slope of line AB is 5/9
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slope of line AB is 1/9
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slope of line AB is 3/9

The fundamental interval, that is the number of division between LFP & UFP on the two scales X and Y are 50 and 150 respectively. The ice point on both the scales is $0 °$ . If the temperature on the X-scale is $15 °$ , then what is the temperature on the Y-scale ?

$1 . 30 ° 2 . 45 ° 3 . 60 ° 4 . 75 °$

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1
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2
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3
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4

Which of the following statement is correct regarding heat transfer?

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Forced convection requires gravity
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Natural convection requires gravity
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Radiation and forced convection requires gravity
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Neither natural nor forced convection requires gravity

A deep rectangular pond of surface area A, containing water (density = $ρ$ , specific heat capacity = s), is located in a region where the outside air temperature is at a steady value of $- 26 {}^{o}C$ . The thickness of the ice layer in this pond at a certain instant is x. Taking the thermal conductivity of ice as k, and its specific latent heat of fusion as L, the rate of increase of the thickness of the ice layer, at this instant, would be given by:

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$\frac{26 k}{xρ (L - 4 s)}$
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$\frac{26 k}{x^{2} ρL}$
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$\frac{26 k}{xρL}$
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$\frac{26 k}{xρ (L + 4 s)}$

Two uniform rods of length L and 2L and thermal coefficient of linear expansion 2 $α$ and $α$ respectively, are connected as shown in the figure. The equivalent coefficient of linear expansion is:

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$\frac{3 α}{4}$
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$\frac{4 α}{3}$
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$\frac{2 α}{3}$
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$\frac{5 α}{3}$

Recently, the phenomenon of super conductivity has been observed at 73 K. This temperature is nearly equal to

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$- 288 ° F$
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$- 146 ° F$
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$- 328 ° F$
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$+ 178 ° F$

If a graph is plotted between temperature of a body on degree Celsius (along y-axis) and degree Fahrenheit [along x-axis] at different temperatures, then the slope of the graph will be:

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$\frac{5}{9}$
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$\frac{9}{5}$
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$\frac{3}{5}$
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$\frac{5}{3}$

Which of the following is true in modern thermometry?

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Triple point of water is fixed
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Boiling point of water is fixed
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Melting point of ice is fixed
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Dew point is fixed

A metal wire of length l and area of cross-section A is fixed at its ends by rigid supports at negligible tension. If this wire is cooled, then the tension in it will be

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Proportional to l
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Inversely proportional to l
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Independent of l
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Independent of A

Which temperature on the Fahrenheit scale is numerically the same as that on the Celsius scale?

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$- 40 ° F$
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$- 42 ° F$
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$- 70 ° F$
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$- 72 ° F$

The absolute zero temperature on the Fahrenheit scale is (approximately):

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$- 273 ° F$
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$- 32 ° F$
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$- 460 ° F$
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$- 132 ° F$

Which of the following statements is correct?

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Natural convection can occur in space having gravity as well as in gravity-free space
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Forced convection occurs in space having gravity only
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Forced convection can occur in gravity-free space
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Natural convection occurs only in gravity-free space

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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