Particle Nature of Electromagnetic Radiations

The energies  ${\mathrm{E}}_1\mathrm{and}{\mathrm{E}}_2$  of two radiations are $25 \mathrm{eV}$ and $50 \mathrm{eV}$, respectively. The relation between their wavelength i.e.,  ${\mathrm{\lambda }}_1\mathrm{and}{\mathrm{\lambda }}_2$ will be:

The value of Planck’s constant is  $6.63\times {10}^{-34}Js.$  The velocity of light is  $3.0\times {10}^{8}m{s}^{-1}.$  Which value is closest to the wavelength in meters of a quantum of light with frequency of  $8\times {10}^{16}{s}^{-1}?$

Name the phenomenon which shows the quantum nature of electromagnetic radiation. 

The frequency of radiation emitted, when an electron falls from $n=3$ to $n=1,$ in a Hydrogen atom would be $\underline{ }$
(Given, ionisation energy of Hydrogen is$2.18\times {10}^{-18} \mathrm{J}/\mathrm{atom}$ and $h=6.625\times {10}^{-34} \mathrm{J}.\mathrm{s} )$

If the maximum kinetic energy of photoelectrons ejected from a metal surface when it is irradiated with a radiation of frequency $4\times {10}^{14}{ \mathrm{s}}^{-1}$ is $6.63\times {10}^{-20} \mathrm{J},$ then the threshold frequency of the metal is _______

$1$ mole of photons, each of frequency $250 {\mathrm{s}}^{-1}$ would have approximately a total energy of $1 \mathrm{e}\mathrm{r}\mathrm{g}$.

Energy of an electron is given by $\mathrm{E}=-2· 178 \times {10}^{-18}\mathrm{J} \left(\frac{{\mathrm{Z}}^2}{{\mathrm{n}}^2}\right)$. Calculate the wavelength of light required to excite an electron in a hydrogen atom from $\mathrm{n}=1 \text{to} \mathrm{n}=2$ will be

The energy difference between the ground state of an atom and its excited state is $4.4\times {10}^{-\mathrm{14 }}\mathrm{J}$, calculate the wavelength of the photon required to induce the transition.

The "Kangri" is an earthen pot used to stay warm in Kashmir during the winter months. Assume that the "Kangri" is spherical and of surface area $7\times {10}^{-2} {\mathrm{m}}^2.$ It contains $300 \mathrm{g}$ of a mixture of coal, wood and leaves with calorific value of $30 \mathrm{kJ} {\mathrm{g}}^{-1}$ (and provides heat with $10\%$ efficiency). The surface temperature of the 'Kangri' is $60°\mathrm{C}$ and the room temperature is $0°\mathrm{C}.$ Then, a reasonable estimate for the duration t (in hours) that the 'kangri' heat will last is (take the 'kangri' to be a black body):

A certain stellar body has radius $50R_s$ and temperature $2T_s$ and is at a distance of $2\times {10}^{10} \mathrm{AU}$ from the earth. Here, $\mathrm{AU}$ refers to the earth-sun distance and $R_s$ and $T_s$ refer to the sun's radius and temperature, respectively. Take, both star and sun to be ideal black bodies. The ratio of the power received on earth from the stellar body as compared to that received from the sun is close to

What is the number of photons of light with a wavelength of $4000 \mathrm{pm}$ that provide $1 \mathrm{J}$ of energy?

Stefan-Boltzmann law states that the energy radiated per unit area per unit time by the black body is

A perfectly black body
 

The approximate value of Planck's constant is equal to _____.

What is the difference between a photon and a quantum ?

Identify the least stable among the following:

a. Li^- 

b. Be^-

c. B^-

d. C^-

The quantum numbers +1/2and -1/2 for the electron spin represen

Using s, p, d, f  notations, describe the orbital with the following quantum numbers.

(d) n=3, l=2

Using s, p, d, f  notations, describe the orbital with the following quantum numbers.

(c) n=5 ,l=3