(i) Ray diagrams for concave lens:
Case 1 – Ray parallel to principal axis:
A ray parallel to the principal axis, after refraction through a concave lens, diverges and appears to come from the focus F₁ on the same side as the incident ray.
Case 2 – Ray directed towards principal focus:
A ray directed towards the focus F₂ on the other side of the lens, after refraction, emerges parallel to the principal axis.
(Diagrams should show the concave lens with both cases marked clearly with arrows and F₁, F₂ labeled.)
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(ii) Given:
Using lens formula:
$$\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$$
$$\frac{1}{v} - \frac{1}{-16} = \frac{1}{24}$$
$$\frac{1}{v} = \frac{1}{24} - \frac{1}{16} = \frac{2-3}{48} = \frac{-1}{48}$$
$$v = -48 \text{ cm}$$
Magnification: $m = \frac{v}{u} = \frac{-48}{-16} = +3$
Image height $= 3 \times 4 = 12$ cm
The image is formed 48 cm on the same side as the object (virtual), erect, and 12 cm tall (enlarged).
Source: Light – Reflection and Refraction, Chapter 9
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