Question

Which is not characteristic of Planck's quantum theory of radiation? (1) Radiation is associated with energy. (2) Energy is neither absorbed nor emitted in whole number or multiples of quanta. (3) The magnitude of energy associated with quanta is proportional to the frequency. (4) Radiation energy is neither emitted nor absorbed continuously but in small packets called quanta.

Short answer

Option 2

Step-by-step solution

Understand Planck's Quantum Theory

Planck's quantum theory states that energy is emitted or absorbed in discrete units called quanta (or photons), not in a continuous manner, and that the energy of these quanta is proportional to the frequency of the radiation.

Analyze Option 1

Option 1 states that 'Radiation is associated with energy.' This is consistent with Planck's theory, as it describes how energy is exchanged through radiation.

Analyze Option 2

Option 2 states that 'Energy is neither absorbed nor emitted in whole number or multiples of quanta.' This contradicts Planck's theory, which specifies that energy is indeed absorbed or emitted in whole number multiples of quanta.

Analyze Option 3

Option 3 states that 'The magnitude of energy associated with quanta is proportional to the frequency.' This is a direct characteristic of Planck's theory, as given by the equation: E = hu.

Analyze Option 4

Option 4 states that 'Radiation energy is neither emitted nor absorbed continuously but in small packets called quanta.' This aligns perfectly with Planck's theory.

Identify the Incorrect Statement

After comparing all the options, it's clear that Option 2 is not a characteristic of Planck's quantum theory. It contradicts the fundamental concept that energy is absorbed or emitted in discrete packets or quanta.

Key concepts

discrete energy levels

In Planck's Quantum Theory, one of the essential ideas is the notion of discrete energy levels. This concept means that electrons in an atom can only exist at specific energy levels, rather than any value in between.
Electrons jump between these levels by either absorbing or emitting a packet of energy, called a quantum.
This is different from the classic view, where energy could change in a smooth, continuous manner. By applying this concept, we can better understand various atomic behaviors and spectra.
Imagine a set of stairs. You can only step on specific steps.
You cannot step halfway between steps. In the same way, electrons can only reside in certain energy levels and not halfway in between.
This step-like behavior is fundamental to many phenomena in physics and chemistry.

quanta emission

Quanta emission refers to the process where atoms and molecules emit energy in discrete packets called quanta.
Quanta are often represented as photons of light. Each photon has a specific amount of energy tied to it.
In Planck's Quantum Theory, the emission occurs when an electron drops from a higher energy level to a lower one, releasing a quantum.
This process helps explain why we see specific lines in atomic spectra rather than a continuous spectrum.
When electrons in an excited state return to a lower energy level, they emit energy in the form of radiation.

The amount of energy released is precisely the difference between the two energy levels involved.
This energy emission is vital in technologies such as lasers and LEDs.
These technologies rely on the controlled emission of quanta for their operation.
Understanding this concept makes it easier to grasp how light and other forms of radiation are generated at the atomic level.

radiation frequency

Radiation frequency is closely linked with the energy of quanta being emitted or absorbed.
According to Planck's Quantum Theory, the energy of a quantum is proportional to the frequency of the radiation (given by the formula: \( E = h u \)).
Here, \( E \) stands for energy, \( h \) is Planck's constant, and \( u \) represents radiation frequency.
This explains why higher frequency radiation (like UV light) has more energy per quantum than lower frequency radiation (like visible light).
In simple terms, the higher the frequency of the light, the more energetic the quanta.
This relation helps us understand phenomena such as why higher frequency X-rays can penetrate materials more effectively than lower frequency radio waves.
Furthermore, radiation frequency is fundamental to various technologies, including medical imaging and communication systems.
Understanding how frequency is tied to energy is crucial for both theoretical and applied physics.