Planck's Quantum Hypothesis

Q. Two bulbs $A$ and $B$ emit red light and yellow light at $8000A^{\circ }$ and $4000A^{\circ }$ respectively. The number of photons emitted by both the bulbs per second is the same. If the red bulb is labelled as $100$ watts, find the wattage of the yellow bulb.

Q.

The dissociation energy of $H_2$ is 430.53 kJ $mo{l}^{-1}$. If hydrogen is dissociated by illumination with radiation of wavelength 253.7 nm, the fraction of the radiant energy which will be converted into kinetic energy is given by

1. 1.22%

2. 8.76%

3. 2.22%

4. 100%

Q. A dye absorbs a photon of wavelength λ and re-emits the same energy into two photons of wavelength ${\lambda }_1$ and ${\lambda }_2$ respectively. The wavelength λ is related with ${\lambda }_1$ and ${\lambda }_2$ as:

1. $\lambda =\frac{({\lambda }_1+{\lambda }_2)}{\left({\lambda }_1{\lambda }_2\right)}$
2. $\lambda =\frac{\left({\lambda }_1{\lambda }_2\right)}{({\lambda }_1+{\lambda }_2)}$
3. $\lambda =\frac{({\lambda }_1^2+{\lambda }_2^2)}{\left({\lambda }_1{\lambda }_2\right)}$
4. $\lambda =\frac{\left({\lambda }_1^2{\lambda }_2^2\right)}{({\lambda }_1+{\lambda }_2)}$

Q. Calculate the wavelength of the radiation which would cause the photo-dissociation of chlorine molecule if the Cl-Cl bond energy is 243 kJ/mol.

1. $493nm$
2. $4900\mu m$
3. $4900nm$
4. $493m$

Q. Calculate the energy in kilocalorie per mole of photons of an electromagnetic radiation having a wavelength of $7600\stackrel{\circ }{A}$.

1. 33.56
2. 37.56
3. 47.35
4. 42.35

Q. What is a packet of energy called?

1. Electron
2. Photon
3. Positron
4. Proton

Q. If a dye absorbs a photon of wavelength $\lambda$ and re-emits the absorbed energy as two photons of wavelength ${\lambda }_1$ and ${\lambda }_2$. Then:

1. $\lambda =\frac{{\lambda }_1+{\lambda }_2}{{\lambda }_1{\lambda }_2}$
2. $\lambda =\frac{{\lambda }_1{\lambda }_2}{{\lambda }_1+{\lambda }_2}$
3. $\lambda =\frac{{\lambda }_1^2{\lambda }_2^2}{{\lambda }_1+{\lambda }_2}$
4. $\lambda =\frac{{\lambda }_1{\lambda }_2}{({\lambda }_1+{\lambda }_2{)}^2}$

Q. A $100W$ power source emits green light having a wavelength of $5000\stackrel{\circ }{A}$. How many photons are emitted per minute by the source?

1. $1.5\times {10}^{20}$
2. $3.5\times {10}^{22}$
3. $1.5\times {10}^{22}$
4. $3.5\times {10}^{20}$

Q. A certain laser transition emits $6.37\times {10}^{15}{\text{quanta sec}}^{-1}{\text{m}}^{-2}$. Calculate the power output in ${\text{J sec}}^{-1}{\text{m}}^{-2}$.
Given: $\lambda =632.8\text{nm}$

1. $2.5\times {10}^{-3}{\text{J sec}}^{-1}{\text{m}}^{-2}$
2. $2.0\times {10}^{-3}{\text{J sec}}^{-1}{\text{m}}^{-2}$
3. $1.6\times {10}^{-3}{\text{J sec}}^{-1}{\text{m}}^{-2}$
4. $2.3\times {10}^{-3}{\text{J sec}}^{-1}{\text{m}}^{-2}$

Q. What is the ratio of the energies of two radiations in which one has a wavelength of $6000\stackrel{\circ }{A}$ the other has a wavelength of $2000\stackrel{\circ }{A}$?

1. $1:3$
2. $1:2$
3. $2:1$
4. $2:3$