Within the electromagnetic spectrum, which of the following types of radiation has the lowest frequency and therefore the longest wavelength?

Introduction / Context:
The electromagnetic spectrum covers a wide range of electromagnetic waves, from very low frequency radio waves to extremely high frequency gamma rays. Each region of the spectrum has different properties and applications. This question tests your knowledge of the relative order of frequency among visible light, gamma rays, X-rays, and ultraviolet rays.

Given Data / Assumptions:

• We are comparing the frequencies of four types of electromagnetic radiation.
• The options are visible light, gamma rays, X-rays, and ultraviolet rays.
• The question specifically asks for the lowest frequency among these.

Concept / Approach:
In the electromagnetic spectrum, frequency increases as we move from radio waves to microwaves, infrared, visible light, ultraviolet, X-rays, and finally gamma rays. Consequently, wavelength decreases in this direction, because the speed of light c is given by c = frequency × wavelength. Among the four given options, visible light lies at a lower frequency region compared to ultraviolet, X-rays, and gamma rays, which are progressively higher in frequency and energy.

Step-by-Step Solution:
Step 1: Recall the basic order of the electromagnetic spectrum from low to high frequency: radio, microwave, infrared, visible, ultraviolet, X-ray, gamma ray. Step 2: Locate each option within this order. Step 3: Visible light comes before ultraviolet, X-rays, and gamma rays, so it has a lower frequency than all of them. Step 4: Therefore, among the provided options, visible light has the lowest frequency.

Verification / Alternative check:
You can think of energy per photon, which is proportional to frequency (E = h * f). Gamma rays are known to be extremely energetic, used in nuclear and high energy processes. X-rays, used in medical imaging, are also highly energetic. Ultraviolet rays have enough energy to cause chemical changes and sunburn. Visible light is less energetic than ultraviolet and therefore has a lower frequency. This energy-based reasoning matches the spectral ordering.

Why Other Options Are Wrong:

• Gamma rays: These have very high frequencies and the shortest wavelengths in the electromagnetic spectrum among the given options, not the lowest frequency.
• X-rays: These have frequencies higher than ultraviolet and visible light and are used for penetrating materials, indicating high energy.
• Ultra violet rays: These have frequencies higher than visible light but lower than X-rays and gamma rays, so they do not have the lowest frequency among the four.

Common Pitfalls:
Students often remember that visible light sits in the middle of the entire spectrum, but forget its position relative to ultraviolet and X-rays. Confusing wavelength and frequency is also common: lower frequency means longer wavelength, and higher frequency means shorter wavelength. Keeping the full order of the spectrum in mind and linking it to common examples (sunlight, medical X-rays, nuclear gamma rays) helps prevent these mistakes.

Final Answer:
Among the given options, visible light has the lowest frequency.