छाया कब बनती है

Options

A. जब वस्तु अपार्दर्शी हो
B. जब प्रकाश के पथ में कोई अपार्दर्शी वस्तु आ जाये
C. जब वस्तु बहुत बड़ी हो
D. सभी

Answer

### Step-by-Step Solution:

1. **Understanding the Concept of Shadow**:
- A shadow is formed when an object blocks the path of light.

2. **Conditions for Shadow Formation**:
- For a shadow to be formed, there are two main conditions that must be met:
- **Presence of an Object**: There must be an object that can block the light. This object can be opaque (not allowing light to pass through) or translucent (allowing some light to pass but not enough to see through clearly).
- **Light Source**: There must be a source of light that illuminates the area. This could be sunlight, a lamp, or any other light-emitting source.

3. **Positioning Relative to Light Source**:
- The position of the object relative to the light source affects the size and clarity of the shadow:
- **Closer to the Light Source**: If the object is closer to the light source, the shadow will appear larger.
- **Farther from the Light Source**: If the object is farther from the light source, the shadow will appear smaller.

4. **Transparency of the Object**:
- If the object is transparent (like glass), it will not form a shadow because light can pass through it without being blocked.

5. **Conclusion**:
- A shadow is formed when an opaque object blocks light from a light source. The size and clarity of the shadow depend on the distance of the object from the light source and the nature of the object (opaque or transparent).