# Planck's Quantum Hypothesis

## Trending Questions

**Q.**

What is the number of photons of light with a wavelength of 4000 pm that provide 1 J of energy?

**Q.**Orbital having 3 angular nodes and 3 total nodes is

- 5p
- 3d
- 4f
- 6d

**Q.**The value of Planck's constant is 6.63 × 10−34 js. The velocity of light is 3.0 × 108 ms−1 . Which value is closest to the wavelength in nanometers of a quantum of light with frequencty of 8 × 1015 s−1

3 × 10

^{7}2 × 10

^{-25}5 × 10

^{-8}4 × 10

^{1}

**Q.**

The wavelength of the radiation emitted, when a Hydrogen atom electron falls from infinity to the stationary state, would be:

Rydberg constant $=1.097\xc3\u2014{10}^{7}{\mathrm{m}}^{-1}$

$91\mathrm{nm}$

$406\mathrm{nm}$

$192\mathrm{nm}$

$9.1\xc3\u2014{10}^{-8}\mathrm{nm}$

**Q.**

Find energy of each of the photons which

(i) correspond to light of frequency 3× 1015 Hz.

(ii) have wavelength of 0.50 Å.

**Q.**The equation E=hv indicates that:

- Photons have both particle and wave nature
- Photons are waves
- Photons are straem of particles
- No such inference can be drawn from the given equation

**Q.**

Rest mass of a photon is _______.

**Q.**

State the postulates of Plancks quantum theory.

**Q.**

An X-ray tube is operated at $1.24millionvolt$. The shortest wavelength of the produced photon will be:

${10}^{-2}nm$

${10}^{-3}nm$

${10}^{-4}nm$

${10}^{-1}nm$

**Q.**Calculate the energy associated with photon of light having a wavelength 6000 oA. [h= 6.626×10−27 erg s]

- 3.313×10−12 erg
- 3.313×10−13 erg
- 3.313×10−10 erg
- 3.313×10−11 erg

**Q.**A wavelength of 450 nm corresponds to :

(1 nm = 10−9 m)

- Frequency(ν) =6.6×1014 Hz
- Wave number(~ν) =2.2×106 m−1
- None of the above
- Both (a) and (b)

**Q.**Suppose 10−17J of energy is needed by the interior of the human eye to see an object, how many photons of green light (λ=550 nm) are needed to generate this minimum amount of energy?

- 22
- 20
- 14
- 28

**Q.**What possibly can be the ratio of the de Broglie wavelength of two electrons having the same initial energy and accelerated through 50 V and 200 V

- 3:5
- 10:3
- 6:2
- 2:1

**Q.**A bulb of 40 W is producing a light of wavelength 620 nm with 80% efficiency. Find the number of photons emitted by the bulb in 20 seconds.

(1 eV=1.6×10−19 J, hc=12423 eV oA)

- 2×1019
- 4×1018
- 5×1021
- 2×1021

**Q.**

Calculate the energy in corresponding to light of wavelength $45nm.$

**Q.**What is quanta?

**Q.**In hydrogen atom, the de Broglie wavelength of an electron in the second Bohr orbit is [Given that Bohr radius, a0=52.9 pm]:

- 211.6 pm
- 211.6π pm
- 52.9π pm
- 105.8 pm

**Q.**Sun glasses have small amount of AgCl incorporated in the lenses. When light of appropriate wavelength is exposed it turns to gray colour to reduce the glare following the reactions:

AgClhv−→Ag (Gray)+12Cl2

If the heat of reaction for the decomposition of AgCl is 248 kJ mol−1. Find the wavelength needed to induce the desired process?

- 4.83×10−7 m
- 9.66×10−7 m
- 2.41×10−7 m
- 4.83×10−6 m

**Q.**

The maximum emission wavelength at temperature $2000K$ is $4\mathrm{\xce\xbc}m$. The maximum wavelength corresponding to temperature $2400K$ will be

**Q.**Calculate the wavelength of a photon having an energy of 3 eV. Take h=6.6×10−34 Js

- 4.125×103∘A
- 5.125×103∘A
- 7.125×103∘A
- 4.125×104∘A

**Q.**A bulb emits light of wavelength (λ)=4500 oA . The bulb is rated as 150 watt and 8 % of its energy is emitted as light. If number of photons emitted is x×1019, then the value of x is:

(Take planck's constant h=6×10−34J s and speed of light c=3×108 m s−1)

**Q.**Calculate the wavelength of a photon having an energy of 2 eV

- 6.21×103∘A
- 6.20×103 nm
- 4.41×103 nm
- 4.41×103∘A

**Q.**

In astronomical observations, signals observed from the distant stars are generally weak. If the photon detector receives a total of 3.15 × 10–18 J from the radiations of 600 nm, calculate the number of photons received by the detector.

**Q.**

How does quantum mechanics differ from classical mechanics?

**Q.**A bulb emits light of λ=4500 oA. The bulb is rated as 150 watt and 8% of the energy is emitted as light. How many photons are emitted by the bulb per second?

- 2.72×1018
- 27.2×1018
- 0.272×1018
- 2.72×1016

**Q.**

How did plank explain the black body radiation?

**Q.**Iodine molecule dissociates into atoms after absorbing light of 4500 oA . If one quantum of radiation is absorbed by each molecule. Calculate the kinetic energy of iodine atoms (bond energy of I2=240 kJmol−1)

- 0.216×10−18 J
- 0.216×10−17 J
- 0.216×10−20 J
- 0.216×10−19 J

**Q.**

How is heat transferred by radiation?

**Q.**What is the ratio of the energies of two radiations in which one has a wavelength of 6000 ∘A the other has a wavelength of 2000 ∘A?

- 1:3
- 1:2
- 2:1
- 2:3

**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.

- 493 nm
- 4900 μm
- 4900 nm
- 493 m