Question

List these three types of electromagnetic radiation-visible, gamma rays, and microwaves-in order of: (a) decreasing energy per photon (b) decreasing frequency (c) decreasing wavelength

Short answer

For decreasing energy per photon and decreasing frequency, the order is Gamma rays > Visible light > Microwaves. For decreasing wavelength, the order is Microwaves > Visible light > Gamma rays.

Step-by-step solution

Identifying Characteristics of Electromagnetic Radiation

The energy of a photon is proportional to its frequency; the higher the frequency, the higher the energy. Frequency and wavelength are inversely proportional to each other. Gamma rays have the highest energy and hence the highest frequency but the shortest wavelengths, microwaves have lower energy, lower frequency, and longer wavelengths compared to gamma rays and visible light. Visible light falls in the middle of the energy and frequency range but varies in wavelength within the visible spectrum.

Ordering by Decreasing Energy per Photon

Since energy is directly proportional to frequency, we can order them by their frequencies. Gamma rays have the highest frequency followed by visible light, and microwaves have the lowest frequency. Hence, in terms of energy per photon: Gamma rays > Visible light > Microwaves.

Ordering by Decreasing Frequency

Frequency decreases from gamma rays to visible light to microwaves because the energy of a photon is directly related to its frequency. The ordering will be: Gamma rays > Visible light > Microwaves.

Ordering by Decreasing Wavelength

Wavelength is inversely proportional to frequency. Thus, as frequency decreases, wavelength increases. The order will be reversed compared to the frequency: Microwaves > Visible light > Gamma rays.

Key concepts

Energy per Photon

To understand the energy that electromagnetic radiation carries, we think of light as being made up of particles called photons. Each photon contains a discrete amount of energy, and this energy can be calculated using the equation:
\( E = h u \),
where \( E \) is the energy per photon, \( h \) is Planck's constant (6.62607015 \times 10^{-34} joule·seconds), and \( u \) is the frequency of the electromagnetic wave. The concept of energy per photon is critical because it helps explain phenomena like why gamma rays can cause damage to biological tissues while visible light, with less energy per photon, does not.

Exercise Improvement Advice

For a learning enhancement, visual aids showing photons with different amounts of energy can be introduced, such as a diagram illustrating photons of gamma rays with more energy impacting material versus photons of visible light with less energy interacting with the same material.

Electromagnetic Spectrum

The electromagnetic spectrum is a way to categorize the different forms of electromagnetic radiation. It ranges from very high-energy gamma rays to low-energy radio waves. As we move from gamma rays to radio waves, the energy per photon decreases which corresponds to a decrease in frequency and an increase in wavelength of the electromagnetic waves. The visible portion of the spectrum is just a tiny part of the overall range and is the spectrum of light that is visible to the human eye. Each range within the spectrum has its unique applications and implications for life on Earth.
For instance, gamma rays are often used in medical treatments, while microwaves are commonly used in communication systems and cooking food.

Real-world Connections

Making connections to daily life like discussing how different wavelengths are utilized in medical diagnostics, consumer electronics, and even art can foster a deeper understanding of the electromagnetic spectrum.

Frequency and Wavelength Relationship

Frequency and wavelength have an inversely proportional relationship, expressed in the equation:
\( c = \lambdau \),
where \( c \) represents the speed of light, \( \lambda \) is the wavelength, and \( u \) is the frequency. This essential relationship means that as the wavelength increases (longer waves), the frequency decreases (fewer waves passing a point per second), and vice versa. Understanding this physical property helps explain why different types of electromagnetic radiation have their characteristic behaviors. For example, it helps us understand why microwaves are suitable for cooking; their longer wavelengths allow them to penetrate and heat food efficiently.

Interactive Activities

To enhance retention, interactive simulations where students can manipulate wavelength and frequency to see their inversely proportional relationship impact could be very effective. This hands-on approach often makes abstract concepts more tangible.