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The electromagnetic spectrum encompasses all types of electromagnetic radiation. This includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Each type of radiation varies in frequency and wavelength.
Radiation types in the electromagnetic spectrum are ordered by frequency and wavelength.

• Low-frequency radiation like radio waves have long wavelengths.
• High-frequency radiation like gamma rays have short wavelengths.

Visible light, which is a small part of the electromagnetic spectrum, can be perceived by the human eye. It ranges from violet (which has a shorter wavelength and higher frequency) to red (which has a longer wavelength and lower frequency). The problem mentioned involves yellow-green light, which the human eye is most sensitive to, and falls somewhere in the middle of the visible spectrum.

Frequency refers to the number of waves that pass a given point in one second. It is measured in Hertz (Hz). In the context of the electromagnetic spectrum, frequency can vary greatly—from a few Hz to many GHz.In the exercise,

• The frequency is given as \(5.5 \times 10^{14} \text{ Hz}\).
• This is characteristic of visible light.

Frequency is fundamentally important to understanding light waves because it relates to the energy of the light. Higher frequency means higher energy. Since the frequency is known, we can calculate the wavelength using the speed of light, making frequency a core part of solving such problems.

The speed of light in a vacuum is a constant and crucial to calculations not just in this problem, but in all of physics. The value is approximately \(3.0 \times 10^8 \text{ m/s}\). The relationship between speed, frequency, and wavelength is expressed in the equation:

• \(c = f \times \lambda \)

This equation shows us that the speed of light \(c\) is the product of the frequency \(f\) and the wavelength \(\lambda\). To calculate a known wavelength or frequency, this equation must be rearranged. Here, it has been used to determine the wavelength of light using its frequency. This knowledge is critical when measuring the physical dimensions light can occupy, such as in the exercise.

Correct unit conversion is pivotal in physics to ensure calculations are accurate. In this problem, we need to convert the physical width of a thumb from centimeters to meters.

• Given: \(2.0 \text{ cm} = 0.02 \text{ m}\)

In the International System of Units (SI), wavelengths are usually expressed in meters. So, converting thumb width to meters ensures consistency and correctness in the calculation.Converting units ensures dimensions are in the same system, allowing calculations to proceed unhampered. Mistakes in unit conversion might lead to significant errors in computations. Understanding unit conversion bridges the gap between problem measurements and proper solutions.