A ray of light after refraction through a concave lens becomes parallel to the principal axis after refraction through the concave lens. Explain with a ray diagram when this can happen.

Explanation

To explain when a ray of light becomes parallel to the principal axis after refraction through a concave lens, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Concave Lens**:
- A concave lens is a diverging lens that is thinner at the center than at the edges. It causes parallel rays of light to diverge after passing through it.

2. **Principal Axis and Focal Point**:
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