Page 234 - Physics_Form_2

Physics for Secondary Schools

(c) Digital cameras are used to capture
Task 6.5 images that can be fed into computers.

An example of a digital camera is
Using locally available materials, shown in Figure 6.16.
design and construct and test a simple
lens camera.
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Uses of cameras

The main function of a camera is to
take photographs. However, specialised
cameras have other additional functions
as follows:

(a) Video cameras are used to take motion
pictures. Figure 6.14 shows a video
camera.

Figure 6.16: A digital camera

Exercise 6.4

1. A photographer used a camera fitted

Figure 6.14: A video camera with a lens having a focal length
(b) Closed-circuit television (CCTV) of 50 mm to take a photograph of
cameras are used for surveillance in a flower that is 5 cm in diameter.
high-security installations, banks, Suppose the flower is placed 20 cm
shopping malls, offices and residences. in front of the camera lens.
Figure 6.15 shows an example of a (a) At what distance from the film
CCTV security camera. should the lens be adjusted to
obtain a sharp image?
(b) What would the diameter of the
image of the flower on the film
be?
(c) What is the nature of the lens
of this camera?

2. You are standing at a point 1.2 m
Figure 6.15: Closed-circuit television
(CCTV) camera in front of a plane mirror while

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Student’s Book Form Two

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