Which of the following has the largest wavelength?

Options

A. Radiowave
B. x-rays
C. Ultraviolet ray
D. Infra-red ray

Answer

To determine which of the given electromagnetic waves has the largest wavelength, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Electromagnetic Waves**: The options provided are:
- Option 1: Radio waves
- Option 2: X-rays
- Option 3: Ultraviolet rays
- Option 4: Infrared rays

2. **Understand the Relationship Between Wavelength and Frequency**:
- The relationship between wavelength (λ) and frequency (f) is given by the equation:
\[ c = λ \cdot f \]
where \(c\) is the speed of light in a vacuum (approximately \(3 \times 10^8\) m/s).
- From this equation, we can derive that:
\[ λ = \frac{c}{f} \]
- This indicates that wavelength is inversely proportional to frequency. Therefore, waves with lower frequencies have longer wavelengths.

3. **Compare the Frequencies of the Given Waves**:
- Radio waves have the lowest frequency among the electromagnetic spectrum.
- X-rays have a higher frequency than radio waves.
- Ultraviolet rays have a frequency higher than X-rays.
- Infrared rays have a frequency that is higher than radio waves but lower than visible light.

4. **Determine the Wave with the Largest Wavelength**:
- Since radio waves have the lowest frequency, they will have the largest wavelength compared to X-rays, ultraviolet rays, and infrared rays.

5. **Select the Correct Option**:
- Based on the analysis, the wave with the largest wavelength is:
- **Option 1: Radio waves**

### Final Answer:
The electromagnetic wave with the largest wavelength is **Radio waves**.

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