Date post: | 13-Dec-2015 |
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A convex lens is like a series of prisms that refract the light by different amounts
The quantity which dictates how much the light is converged is the focal length of the lens.
This is a rough method of measuring the focal length of a convex lens
Measure the distance from the lens to the image (wall or screen) to obtain a rough value of the focal length of the lens.
The distance between the lens and screen varies with focal length, i.e. the thicker the lens the shorter the focal length.
The images produced by cameras and projectors need to be focussed onto a screen or film etc. To do this it is necessary to move the lens.
For example, if the object is moved towards the camera the lens would need to move away from the film.
NB•Virtual images cannot be projected onto a screen but are the right way up.•Real images can be projected onto a screen and are inverted.
Magnification
magnification = image size/object size
Example:The magnifying glass is used to view a jewel of size 3mm. The image size observed is 1.2cm. Calculate the magnification.
Mag = 1.2/0.3 = x4
Calculate the magnification for the Camera, Projector & Magnifying Glass using the sizes from your diagrams.