For convex lens the focal length is positive. On the other hand, the focal length of concave lens is negative. Thus, for convex lens, the focal length is a distance over which all the parallel rays will converge. A certain point over that distance all the parallel rays will converge, that point is known as focal point.
answer:THE ANSWER IS D.
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Focal length (shown in red) is the distance between the center of a convex lens or a concave mirror and the focal point of the lens or mirror — the point where parallel rays of light meet, or converge.
Focal length is the distance between the center of a convex lens or a concave mirror and the focal point of the lens or mirror the point where parallel rays of light meet.
The answer is 33 cm.
We are asked to get the focal length of the convex mirror. We can do this using the mirror equation:
In this particular problem
(distance of the image)
(distance of the object)
note that we used the sign convention for this particular equation.
is negative (-) if the image is formed behind the mirror.
Now, substituting the values that we have, we get:
The sign just signifies that it is, in fact, a convex mirror.
Therefore, the focal length of the convex mirror used is 33 cm.
I hope this helps.