The difference between soft and hard X-rays is of:

Options

A. velocity
B. intensity
C. frequency
D. polarisation.

Explanation

To solve the question regarding the difference between soft and hard X-rays, we can break it down into several steps:

### Step 1: Understand the Definition of X-rays
X-rays are a form of electromagnetic radiation with wavelengths shorter than ultraviolet light and longer than gamma rays. They are categorized into soft and hard X-rays based on their energy and frequency.

### Step 2: Define Soft and Hard X-rays
- **Soft X-rays**: These have lower energy and longer wavelengths. They typically range from about 0.1 to 10 keV (kilo-electron volts).
- **Hard X-rays**: These have higher energy and shorter wavelengths, usually ranging from about 10 keV to 100 keV or more.

### Step 3: Analyze the Properties
The key properties that differentiate soft and hard X-rays include:
- **Energy**: Hard X-rays have higher energy compared to soft X-rays.
- **Frequency**: The frequency of hard X-rays is higher than that of soft X-rays.
- **Wavelength**: Hard X-rays have shorter wavelengths than soft X-rays.

### Step 4: Establish the Relationship between Energy and Frequency
The energy (E) of electromagnetic radiation is directly proportional to its frequency (ν), given by the equation:
\[ E = hν \]
where \( h \) is Planck's constant. This means that as the frequency increases, the energy also increases.

### Step 5: Conclusion
From the above analysis, the primary difference between soft and hard X-rays is their frequency. Hard X-rays have a higher frequency compared to soft X-rays, which correlates with their higher energy.

### Final Answer
The difference between soft and hard X-rays is primarily in their frequency.

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