Focal Length of a Given Lens

The experiment that I am going to do is to investigate the factors that affect the focal length of a lens, I will be also investigate the factor which affects the focal length of a lens. I can decide whether to choose convex lens or concave lens. The difference between those two lenses it that convex lenses are thicker in the middle than at the edges. They refract toward the centre. Whether concave lenses are thinner in the middle than at the edges. When light passes through concave lenses always bend away from each other toward the edges of the lens. I have decided to choose the convex lenses in my experiment. After I have finished with the experiment I will write a conclusion to summarise how the task went, what was the results and what was the overall effect of the experiment.

Background information

There are two different types of lens, convex and concave lenses.

Convex lenses are thicker in the middle than they are on the outside

whereas concave lenses are thicker on the outside than in the middle.

Light rays passing through a concave or diverging lens are bent away

from the principal axis of the lens (the line passing through the

center of the lens, or optical center, at right angles to the lens).

Light rays passing through a convex or converging lens are bent

towards the principal axis.

The dependent variable is the distance l, the distance between the two

positions of the lens.

The independent variable is the distance d, the distance between the

screen and the illuminated object.

The controlled variable is the intensity of the illuminated object and

the focal length of the lens

Prediction

I think that object one will have a very long focal length as the

lines are going to have time to spread out before they reach the lens

where they will be bent

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