Which has the longest wavelength

Options

A. infrared light
B. ultraviolet light
C. radio-waves
D. X-rays

Explanation

To determine which type of electromagnetic wave has the longest wavelength, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Electromagnetic Spectrum**: The electromagnetic spectrum consists of various types of waves arranged according to their wavelengths and frequencies. The types of electromagnetic waves include gamma rays, X-rays, ultraviolet rays, visible light, infrared rays, microwaves, and radio waves.

2. **Identify the Order of Wavelengths**: In the electromagnetic spectrum, the waves are arranged in order of decreasing frequency and increasing wavelength. The order from shortest wavelength to longest wavelength is:
- Gamma rays (shortest wavelength)
- X-rays
- Ultraviolet rays
- Visible light
- Infrared rays
- Microwaves
- Radio waves (longest wavelength)

3. **Determine the Longest Wavelength**: From the arrangement above, it is clear that radio waves have the longest wavelength compared to all other types of electromagnetic waves.

4. **Conclude the Answer**: Therefore, the type of electromagnetic wave with the longest wavelength is **radio waves**.

### Final Answer:
The answer is **radio waves**.

---