Physics 5054 · O Level · Thin lenses

Thin lenses — practice question

Some glass lenses act as converging lenses, whereas others act as diverging lenses. Fig. 5.1 presents the cross-section of a converging lens, the principal axis and the two principal focuses (focal points) $F_1$ and $F_2$ on a full-scale grid.
(a)[1]

Draw a cross-section of a diverging lens.

(b(i))[1]

Using Fig. 5.1, determine the lens focal length.

(b(ii))[1]

On Fig. 5.1, place a vertical arrow of height 2.1 cm at a distance of 3.0 cm from the centre of the lens, and label the arrow O. This arrow represents the object.

(b(iii))[3]

On Fig. 5.1, use two rays from the tip of the object arrow to locate the tip of the image. Then draw a further arrow to represent the image.

(b(iv))[2]

Using the image marked on Fig. 5.1 in (b)(iii), determine the linear magnification obtained.

(b(v))[1]

Explain whether the object's image is real or virtual.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Lens narrower at the centre than at the edges

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