The radiation with highest wave number

Options

A. Microwaves
B. X-rays
C. I.R - rays
D. Radiowaves

Answer

To determine which radiation has the highest wave number among the given options, we can follow these steps:

### Step 1: Understand Wave Number
Wave number (ν̅) is defined as the number of wavelengths per unit distance and is given by the formula:
\[ \nu̅ = \frac{1}{\lambda} \]
where \( \lambda \) is the wavelength. This implies that wave number is inversely proportional to wavelength.

### Step 2: Recall the Order of Wavelengths
We need to know the order of electromagnetic radiation based on their wavelengths. The order from shortest wavelength to longest wavelength is:
1. Gamma rays
2. X-rays
3. Ultraviolet (UV) rays
4. Visible light
5. Infrared (IR) rays
6. Microwaves
7. Radio waves

### Step 3: Determine the Order of Wave Numbers
Since wave number is inversely proportional to wavelength, the order of wave numbers (from highest to lowest) will be the reverse of the order of wavelengths:
1. Gamma rays (highest wave number)
2. X-rays
3. Ultraviolet (UV) rays
4. Visible light
5. Infrared (IR) rays
6. Microwaves
7. Radio waves (lowest wave number)

### Step 4: Analyze the Given Options
The options provided are:
1. Microwaves
2. X-rays
3. Infrared (IR) waves
4. Radio waves

From our analysis, we can see that:
- Microwaves have the longest wavelength and therefore the lowest wave number.
- Infrared (IR) waves have a longer wavelength than X-rays.
- Radio waves have the longest wavelength and the lowest wave number.

### Step 5: Identify the Radiation with the Highest Wave Number
Among the options, X-rays have a higher wave number than both microwaves and infrared waves. Therefore, the radiation with the highest wave number from the options given is:

**Answer: X-rays (Option 2)**

---