Planck's quantum theory-MCQs-Jayam chemistry learners
MCQs of Planck's quantum theory
Introduction:
Planck's quantum theory brought a revolutionary change in
the character of light radiation. In early 1600, people considered light was a
propagating wave of radiant energy. Although light acts as a wave during
propagation, when light interacts with matter behaves as a particle. And it was
invented by Max Planck in 1900. And he became the father of quantum mechanics
with his quantum theory hypothesis.
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high-resolution picture.)
Table of contents:
Video description of
Planck quantum theory
Multiple choice questions and answers on Planck quantum theory
PPT notes of Planck quantum theory
Mind map of Planck
quantum formula
Planck's quantum theory discusses three postulates for energy transitions between the bodies. The postulates of Planck's quantum theory are here.
- Energy changes in a body occur discontinuously as small discrete chunks called quantum.
- In the case of light, the intermittent energy packets are photons. And the magnitude of the photon varies directly with the frequency of emitted light radiation.
- A fractional quanta is inexistent. Besides, a body must accept or release a whole number multiples of quantum periodically at regular intervals. It quantized energy transitions between two objects.
In this way, Planck's quantum theory overcomes the limitations of classical energy assumptions while light interacts with matter. Moreover, it started a new era of particle physics.
Video description of Planck quantum theory:
 |
| Planck quantum theory video description |
Planck's quantum
theory depicts the magnitude of energy exchanges by the bodies. We know an
object accepts or releases energy to the surrounding bodies. The process of
energy transmission is a continuous process following classical physics
assumptions.
But it did not match
in the case of thermal emissions by the blackbody under constant temperature
conditions. So, Max Planck corrected it with the predictions of particle
character of energy. He called it quantum, a minimum quantity of discrete
energy bundle that a body can transmit.
Since then, the dual
nature of energy came into light and raised the curtains to the new era of
particle physics.
A body can neither
absorb nor emit a fractional energy packet less than a quantum. Moreover,
Planck confirmed that a whole number of integral energy chunk participates in
the energy transmission process. In this way, it quantized energy interactions
with matter.
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the video that explains the three postulates of Planck quantum theory.
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Multiple choice questions and answers on Planck quantum theory:
1. Which nature of light is explained by Planck's quantum
theory?
A. Wave
B. Magnetic
C. Particle
D. Object
Answer: Particle
Explanation:
Planck's quantum theory proves the particle nature of light experimentally with the photoelectric effect and black body radiation.
2. What do you mean by 'quantum' in Planck's quantum theory?
A. A bundle of frequency of light
B. A chunk of light energy
C. A packet of energy
D. Another name for electromagnetic radiation
Answer: A packet of energy
Explanation:
According to Planck's quantum theory, the quantum is the
minimum amount of energy emitted or absorbed by the body.
3. Who discovered quantum theory?
A. James Clerk Maxwell
B. Max Planck
C. Isaac Newton
D. Heinrich Hertz
Answer: Max Planck
Explanation:
In 1900,
Max Planck explained the particle nature of light with his theory known as
Planck's quantum theory.
It solved
the mysteries of black body emissions in the ultraviolet region.
4. What is the name for a bundle of light energy in Planck’s
quantum theory?
A. Proton
B. Positronium
C. Photon
D. Protium
Answer: Photon
Explanation:
Photon denotes the bundle of light energy in Planck’s
quantum theory.
Additional reference:
An infographic on the photon of light
5. Which of the following expresses the particle nature of
light?
A. Interference
B. Diffraction
C. Photoelectric effect
D. Spin-orbit coupling
Answer: Photoelectric effect
Explanation:
The photoelectric effect explains the particle nature of
light.
The photoelectric effect is the minimum frequency of light
required to eject an electron from the metal surface.
Since the photoelectric effect restricts to a particular
electron on the metal surface, it explains the particle character.
6. Planck's quantum theory is based on____________
A. Classical physics
B. Electromagnetic theory
C. Quantum mechanics
D. Atomic physics
Answer: Quantum mechanics
Explanation:
It is the basic theory of quantum mechanics. And it paved
the way for the dual character of matter.
Previously, scientists considered that matter and energy
were two unrelated separate entities with unique behavior.
Later, they accepted the dual behavior of matter and light
proposed by de-Broglie.
7. What is Planck's quantum equation?
A. E = hν
B. E = h (f-f0)
C. E = ncq
D. E = nh/2π
According
to it, the energy of light radiation varies directly with its frequency.
So, an
increase in the frequency of emitted or absorbed light radiation increases its
energy. And vice versa.
8. Which of the following is not a postulate of Planck’s
quantum theory?
A. A body emits discrete packets of energy discontinuously.
B. The magnitude of energy of a photon varies directly with
its frequency.
C. A body cannot emit or absorb whole number multiples of
energy.
D. The minimum energy absorbed by the body is a quantum.
Answer: A body cannot emit or absorb whole number multiples
of energy.
Explanation:
According to Planck's
quantum theory, a body exchanges a whole number of multiples of energy
particles.
Moreover, an object cannot
accept or release energy bundle fractions with its surroundings.
9. Planck's quantum theory contradicts which of the
following law?
A. Newton's motion law
B. Rayleigh-Jeans law
C. Pauli's exclusion law
D. Wien's displacement law
Answer: Rayleigh-Jeans law
Explanation:
Experiments
of Rayleigh and Jeans on black bodies ended with the assumption of ultraviolet
catastrophe.
This
theoretical assumption of Rayleigh-Jeans law deviated from practical
observations of black body emissions at the shorter wavelengths.
Quantization of
blackbody emissions solved ultraviolet catastrophe limitation as elucidated by
Rayleigh-Jeans law.
10. What is the relationship between the energy and
frequency of light in Planck’s quantum theory?
A. E = hν
B. E = hν/λ
C. E = hcν
D. E = hc/ν
So,
low-frequency radiations contain low energy. Conversely, high energetic
radiations possess high frequencies.
It
indicates the frequency of radiation expresses its associated energy.
11. Who explained the photoelectric
effect following quantum theory?
A. Rayleigh & Jeans
B. Heinrich Hertz
C. Isaac Newton
D. Gustav Kirchhoff
Answer: Isaac Newton
Isaac Newton supported the quantum nature
of light proposed by Max Planck and explained the photoelectric effect.
When an incident light strikes the metal
surface, two things will happen. A part of a photon's energy removes the
electron from the metal surface by overcoming its binding energy. It is called
threshold energy.
The remaining photon's energy helps in
the motion of the photoelectron. It indicates the conversion of light energy
into the kinetic energy of the photoelectron.
12.
What is the shape of the black body curve following Max Planck quantum
predictions?
A. Straight line parallel to X-axis
B. Inverted U-shaped curve
C.
Straight line parallel to Y-axis
D. Distorted circular
Answer: Inverted U-shaped curve
Explanation:
Max Planck expressed the energy of
electromagnetic radiation in terms of its frequency at different temperature
conditions.
At low temperatures, the black body emits
less energetic radiations.
With the increase in temperature, the
black body expels high energetic radiations.
It
indicates the frequency of black body radiations varies directly with the
temperature.
As mentioned earlier, the black body
cannot lose energy continuously at each temperature.
Instead, it expels discrete amounts of
energy at periodic intervals corresponding to the temperature change.
The assumption of erratic energy
emissions by the black body solved the heavy energy change in the ultraviolet
region as predicted by Rayleigh-Jeans law leading to ultraviolet catastrophe.
It solved the puzzle of black body
radiations not explained by classical mechanics.
Rather than a smooth curve, Planck's assumptions gave an inverted U-shaped curve for the intensity of black body radiations. And it matches closely with the experimental results.
13. When did Planck put forward his
quantum model?
A. 1900
B. 1913
C. 1885
D. 1864
Answer: 1900
Explanation:
Max Planck discovered
the quantum theory in 1900 to depict the particle nature of electromagnetic
radiation.
14. The temperature of the enclosure
containing white light increases. Then what happens to the wavelength of
emitted light if it follows Planck's quantum theory?
A. Wavelength increases with temperature
B. Wavelength decreases with an increase
in temperature
C. Wavelength is independent of the
temperature of the enclosure
D. Wavelength of light depends on the
nature of the metal used in the enclosure
Answer: Wavelength decreases with an
increase in temperature
Explanation:
The energy of a photon varies inversely
with the wavelength of the light radiation.
Radiations with longer wavelengths have
lower energies. And shorter wavelength radiations are highly energetic.
So, with an increase in temperature
(thermal energy) of the enclosure, the wavelength of emitted light radiation
decreases.
15. In which of the following conditions,
when does light acts as a particle?
A. When it transfers from one body to the
other
B. When it interacts with the metal
surface
C. When it travels in a vacuum
D. When the oscillating electrons of
light transfers energy continuously
Answer: When it interacts with the metal
surface
Explanation:
The photoelectric effect is a phenomenon
that expresses the particle nature of light.
When light radiation strikes a metal
surface, it ejects the electron from the metal surface if its frequency is
greater than the threshold frequency.
16. What is the relationship between the photon’s energy and the wavenumber of emitted light radiation?
A. Wavenumber of the emitted photon
increases with the increase in its energy
B. Wavenumber of the emitted photon
increases with the decrease in its energy
C. Wavenumber of the photon is
independent of the energy of light
D. none of the above
Answer: The wavenumber of the emitted
photon increases with the increase in its energy
Explanation:
The wavenumber of the light radiations
varies directly with its photon energy.
A photon with a higher wavenumber has higher energy. Conversely, lower energy photon has lower wavenumber.
17. Why did Planck put forward the
quantum theory?
A. To explain the dual nature of light
B. To explain the electromagnetic nature
of light radiation
C. To streamline the black body radiation
emissions
D. To describe the spin motion of the
oscillating electron
Answer: To streamline the black body
radiation emissions
Explanation:
Classical physics assumed that the black
body emits energy continuously. It leads to the excess release of radiant
energy in the ultraviolet region at shorter wavelengths.
It is named ultraviolet catastrophe. This
theoretical assumption diverges from the practical observations of black body
radiations.
Max Planck put forward his quantum theory
to explain the drawbacks of black body emission proposals of classical physics.
Planck elucidated that the black body
emits energy discontinuously in small installments known as quantum rather than
continuously.
This concept of discrete photon emissions by black body radiations matched closely with the experimental results and corrected the limitations of classical physics.
18. Which postulate of Planck's quantum theory explains the particle nature of light?
A. Energy transfers from one body to
another discontinuously.
B. The magnitude of energy varies
directly with the frequency of light
C. An object can emit or absorb whole
number multiples of quantum
D. The intensity of blackbody radiations
depends on the temperature of the enclosure
Answer:
Energy transfers from one body to another discontinuously.
Explanation:
A body can absorb and emit
discontinuously tiny packets of energy.
Each small energy packet is known as a
quantum.
He discovered the term
"quantum" to denote the minimum amount of energy emitted or absorbed
by the oscillator.
19. Planck's quantum theory supports
A. Dual nature of light
B. Electromagnetic nature of light
C. interaction of a photon with matter
D. magnetic nature of oscillating
electron
Answer: interaction of a photon with
matter
Explanation:
Planck's quantum theory deals with the
particle nature of light. It explains the light interaction with matter.
20. Planck's quantum theory applies to
which region of the electromagnetic spectrum?
A. From radio waves to gamma rays
B. From infrared region to ultraviolet
region
C. From visible zone to ultraviolet
region
D. From Microwave region to visible
region
Answer: From radio waves to gamma rays
Explanation:
Planck's quantum theory explains the
nature of light. Light is electromagnetic radiation. So, Planck's quantum
theory applies to the whole electromagnetic spectrum.
21. Which of the following is a
limitation of Planck’s quantum theory?
A. It did not explain the wave nature of
light
B. It did not explain the velocity of
light
C. It only applies to non-periodic
systems
D. It only considers electron oscillation
rather than atomic oscillations
Answer: It only applies to non-periodic
systems
Explanation:
It described the energy emissions of
periodic systems. It does not apply to non-periodic objects.
22. Which of the following is not an
application of Planck's quantum theory?
A. Fiber optic telecommunications
B. Lasers
C. Pendulum clock
D. MRI scan
Answer: Pendulum clock
Explanation:
The pendulum clock works on the principle
of periodic motion.
23. Atomic clocks of satellites
follow_________________
A. Electromagnetic theory
B. Quantum physics
C. Pendulum motion principle
D. Vibrational motion theory
Answer: Quantum physics
Explanation:
Atomic clocks fitted in satellites for
GPS navigation follow quantum physics.
24. Which of the following energy
notation is following Planck's quantum theory?
A. 3.33 joules
B. 3/4 joules
C. 0.334 joules
D. 3 joules
Answer: 3 joules
Explanation:
A body can accept or release whole number
multiples of quantum. For example- an object can give or take 1hν, 2hν, or 3hν,
nhν units of energy.
Energy in fractions of a quantum can neither emitted nor absorbed. For example- an object cannot transmit 1/2hν, 3/2hν, or 5/4hν units of energy.
25. What is an ultraviolet catastrophe?
A. Excess energy emissions in the
ultraviolet region
B. Excess energy absorption in the
ultraviolet region
C. The wavelength of light fall in the
ultraviolet region
D. The intensity of light in the
ultraviolet region
Answer: Excess energy emissions in the
ultraviolet region
Explanation:
Experiments of Rayleigh and Jeans on
black body ended with the assumption of ultraviolet catastrophe.
The Rayleigh-Jeans law explained the
variation of light intensity with wavelength at a particular temperature (T).
This law states that the light intensity
increases enormously unbounded at shorter wavelengths of the black body
radiations.
It causes excess radiant energy emission by the black body in the ultraviolet region. It is named ultraviolet catastrophe.
PPT notes of Planck quantum theory:
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| PPT of Planck quantum theory |
Planck quantum theory
is the foundation of quantum mechanics that explains the interaction of light
with matter. The physicist Max Planck introduced the term quantum to depict the
quantity of energy.
The magnitude of
radiant energy is the multiplicative product of Planck's constant and the
frequency of emitted radiation. It is Planck quantum law.
E=hν
All energy forms are transmitted as integral
bundles of quanta intermittently. It is the condition of energy quantization.
The shreds of
evidence, such as the photoelectric effect, dual nature of light, and atomic
line spectra, support the particle nature of electromagnetic energy with
matter. Here is an image link pointing to Planck quantum theory evidence.
Click the right side image to open our PowerPoint presentation on Planck quantum theory.
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Mind map of Planck quantum formula:
 |
| Planck quantum formula |
(Click the image to view our mind map on Planck quantum formula)
Planck quantum formula
defines the amount of energy that an object can exchange. The magnitude of the
energy bundle is the product of a fixed numerical value known as Planck's
constant with the radiation frequency. And the E value is a whole number signifying
the integral multiples of quantum. Fractional quantum never exists, according
to Max Planck.
The Planck quantum law
is not limited only to radiation frequency. Further, we can extend it to
wavelength and wavenumber of light. In this case, in addition to Planck's
constant, the speed of light in a vacuum contributes to measuring the energy
particle size. The three different forms of Planck quantum law are here;
E = hν
E = (19.878 x 10-26)/λ
E = (19.878 x 10-26) x ῡ
Numerical problems of Planck's quantum theory:
Question-1:
Answer:
The wavelength of emitted light radiation = 400 nm
According to Planck's law, we have;
E=19.878 x 10-26 Jm/λ
E= 19.878 x 10-26
Jm/400 x 10-9 m
E=0.0496 x 10-17 J
Question-2:
Answer:
The frequency of
emitted light radiation = 4.67x1013 Hz
According to Planck's
law, we have;
E= (6.626 x 10-34
Js) x ν
E= (6.626 x 10-34
Js) x 4.67x1013 Hz
E= 30.943 x 10-21
J
Question-3:
Answer:
The wavelength of
emitted light radiation = 200 m
According to Planck's
law, we have;
E = 19.878 x 10-26
Jm/λ
E = 19.878 x 10-26
Jm/200 = 0.09939 J
The formula to calculate
the wavenumber of photon is
E = 19.878 x 10-26
Jm x Ῡ
0.9939 x 10-26
J = 19.878 x 10-26 Jm x Ῡ
Ῡ = 0.09939 x 10-26
J/19.878 x 10-26 Jm
Ῡ = 0.005 m
For more numerical problems, visit our blog post "Planck quantum theory-numerical problems"
Match the following table on Planck's quantum theory:
| Column-A | Column-B |
|---|---|
| A. Light is a wave | 1. Energy particle |
| B. Quantum | 2. Interaction of light with matter |
| C. Energy as packets | 3. Max Planck |
| D. Photoelectric effect | 4. James Clerk Maxwell |
Answers for the above match the following table are A-4, B-1, C-3, and D-2.
You can download the
above table from the link match the following provided here.
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