A lit candle is set near a thin converging lens, and the candle is treated as the object. A white, vertical screen is shifted to a point on the side of the lens opposite the candle. Fig. 6.1 is a full-size, graph-paper drawing of the lens and the screen.
The focal length of the lens is 2.4 cm. The screen is 7.2 cm from the centre of the lens. A sharply focused, inverted image of the candle is formed on the screen, as shown in Fig. 6.1.
(a)[1]
Define focal length.
(b(i))[1]
On Fig. 6.1, indicate and label each of the two focal points (principal foci) of the lens with an F.
(b(ii))[3]
$Y$ is the tip of the image. On Fig. 6.1, construct a ray diagram to determine where the top of the object is. Label this point $X$.
(b(iii))[1]
Using Fig. 6.1, find the candle’s distance from the centre of the lens.
Worked solution & mark scheme
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