Thermal Properties of Matter

The plots of intensity against wavelength for three black bodies at temperatures $T_1$, $T_2$ and $T_3$ are as shown. The wavelengths are such that

A metal sphere cools at a rate of $2^\circ\text{C/min}$ when the temperature is $80^\circ\text{C}$. If the temperature of the surroundings is $30^\circ\text{C}$, then the rate of cooling when its temperature is…

A spherical blackbody of radius $10\ m$ is maintained at a temperature $T$, radiating power $P$ with a peak emission wavelength $5000\ \AA$. If the body is compressed uniformly such that its radius becomes $R/2$, while…

Coefficient of linear expansion of brass and steel rods are $\alpha_1$ and $\alpha_2$. Lengths of brass and steel rod are $l_1$ and $l_2$ respectively. Though the temperature of brass and steel is increased, $(l_2 -…

If the temperature of $5$ kg mass of a material of a specific heat capacity $200$ J/kg $^\circ$C rises from the $30^\circ$C to $40^\circ$C. The heat received is

A resistance thermometer has resistance $95\ \Omega$ at the ice point and $140\ \Omega$ at the steam point. The resistance obtained if the actual temperature is $30^\circ\text{C}$ is

Three spheres P, Q and R, having radii of 2 m, 3 m and 4 m respectively, are coated with lamp-black on their outer surfaces. The wavelengths corresponding to maximum intensity are 200 nm, 300 nm and 400 nm respectively.…

A cylindrical rod with one end in a steam chamber and the other end in ice results in melting of $0.1$ gram of ice per second. If the rod is replaced by another with half the length and double the radius of the first,…

If the radiant heat absorbed by the body is $75\%$ of the incident heat and if the coefficient of the reflection is $0.15$, then the coefficient of transmission is

The thermal conduction rate '$P_{cond}$' of a slab is given by $P_{cond} = \dfrac{kA(T_1 - T_2)}{x}$, where ' $x$ ' is the thickness of the slab and 'A' is the area . The term that represents thermal resistance ' $R_T$'

The rate of dissipation of the heat by a black body at temperature $T$ is $Q$. The rate of dissipation of heat by ordinary body of the same area at temperature $3T$ and having emissivity $0.25$, will be nearly

A metal sphere cools from $80^\circ\text{C}$ to $60^\circ\text{C}$ in 10 minute. The time taken (in minute) by it to cool from $60^\circ\text{C}$ to $40^\circ\text{C}$ if the room temperature is $30^\circ\text{C}$, is