Thermal properties of matter practice · Mixed difficulty

At temperature $'T'$, the power radiated by a body is $Q$ watt. At the temperature $3T$ the power radiated by it will be

During process of melting, thermal energy that is absorbed during process of melting is called:

A black body is at $727^{\circ} \mathrm{C}$. It emits energy at a rate which is proportional to

Assertion: $H_2$ is found more as compared to $N_2$ in earth's upper atmosphere.
Reason: $N_2$ is heavier than $H_2.$

Temperatures of two stars are in the ratio 3:2. If wavelength of maximum intensity of first body is 4000 $A$, what is corresponding wavelength second body?

On a cold morning, a metal surface will feel colder to touch than a wooden surface because

Two thermally insulated vessels 1 and 2 are filled with air at temperatures $\left( {{T_1},{T_2}} \right)$ volume $\left( {{V_1},{V_2}} \right)$ and pressure $\left( {{P_1},{P_2}} \right)$ respectively. If the valve joining the two vessels is opened, the temperature inside the vessel at equilibrium will be

The temperature of the sun is measured with

The cofficient of volume expansion of a liquid is $\boldsymbol{\gamma}$, it is filled in a container of a material having the coefficient of linear expansion $\boldsymbol{\alpha}$. If the liquid overflows on heating:

A steel tape gives correct measurement at $20^{\circ} \mathrm{C}$. A piece of wood is being measured with the steel tape at $0^\circ \mathrm{C}$. The reading is $25 \mathrm{~cm}$ on the tape, the real length of the given piece of wood must be

The reading of brass scale at room temperature is ${L}_1$. Above room temperature reading is ${L}_2$ and below room temperature reading is $L_3$. Then, relation between the readings is

A glass flask of volume one litre at ${0^0}C$ is fille, level full of mercury at this temperature. The flask and mercury are now heated to ${100^0}C$. How much mercury will spill out, if coefficient of volume expansion of mercury is $1.82 \times {10^{ - 4}}/$ and linear expansion of glass is $0.1 \times {10^{ - 4}}/$ respectively

For a perfectly black body the energy radiated per unit time per unit area is directly proportional to

The relationship between pressure and the density of a gas expressed by Boyle’s law, $P = KD$ holds true

Four identical calorimeters painted in different colours, are heated to same temperature and then allowed to cool in vacuum. Which will cool fastest?

The velocity of heat radiation in vacuum is

For an opaque body coefficient of transmission is

Newton’s law of cooling is a special case of

We consider the radiation emitted by the human body. Which of the following statements is true?

A sphere, a cube and a dise all of the same material, quality and volume are heated to $600^{\circ} \mathrm{C}$ and left in air. Which of these will have the lowest rate of cooling?

(A): Woolen clothes keep the body warm in winter.
(R): Air is a bad conductor of heat.

A steel meter scale is to be ruled so that millimeter intervals are accurate within about $5 \times {10^{ - 5}}mm$ at a certain temperature. The maximum temperature variation allowable during the ruling is (Coefficient of linear expansion of steel $= 10 \times {10^{ - 6}}{K^{ - 1}})$

Assertion (A): The dentistry of water remains constant as it is cooled from room termperature until its temperature reaches $4^{\circ} \mathrm{C}$.
Reason (R): Below $4^{\circ} \mathrm{C}$, the density increases

The temperature gradient in a rod of $0.5m$ long is ${80^0}C/m$ . If the temperature of hotter end of the rod is ${30^0}C$, then the temperature of the cooler end is

The temperature at the two ends $A$ and $B$ of a rod of length $25 \mathrm{~cm}$ and circular cross-section are $100^{\circ} \mathrm{C}$ and $0^{\circ} \mathrm{C}$, respectively. In the steady state, the temperature at a point $10 \mathrm{~cm}$ from the end $B$ is (Ignore loss of heat from curved surface of the rod)

In a room where the temperature is ${30^0}C$, a body cools form ${61^0}C$ to ${59^0}C$ in 4 min. The time (in minutes) taken by the body to cool from ${51^0}C$ to ${49^0}C$ will be

A pressure cooker contains air at $1\;atm$ and ${30^ \circ }C.$ If the safety value of the cooler blows when the inside pressure $\ge 3\;atm,$ then the maximum temperature of the air, inside the cooker can be

Ice, water and steam co-exist at triple point temperature 273.16K and pressure 4.6mm Hg. In a system in which the triple point conditions of temperature and pressure exist, the pressure is increased a little while keeping the temperature constant, then the system contains

The ratio of radiant energies radiated per unit surface area by two bodies is 16 : 1, the temperature of hotter body is $1000K$ , then the temperature of colder body will be

A composite slab is prepared by pasting two plates of thicknesses $\mathrm{L}_1$ and $\mathrm{L_2}$ and thermal conductivities $\mathrm{K}_1$ and $\mathrm{K}_{{2}}$. The slabs have equal Cross-sectional area. Find the equivalent conductivity of the slab.