Draw ray diagram showing the image formation by a concave lens when an object is placed at the focus of the lens.

Explanation

To draw a ray diagram showing the image formation by a concave lens when an object is placed at the focus of the lens, follow these steps:

### Step-by-Step Solution:

1. **Draw the Concave Lens**: Start by drawing a concave lens in the center of your diagram. A concave lens is thinner at the center and thicker at the edges.

2. **Draw the Principal Axis**: Draw a horizontal line through the center of the lens. This line is called the principal axis.

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