Question

how can we identify convex and concave lens without touching them?

Answer 1

To differentiate between convex lens and concave lens simply use few LASER lights and arrange them in parallel taking some distance and place the lens one by one firstly if the LASER lights converge at a point in the direction of the light then that lens is convex and if the light diverge after passing through the lens then the lens used is concave lens.


Or


Place it on a paper (obviously written) if the image of paper gets magnified >1 (i.e larger than original) then its convex lens else concave(magnification<1)...

Answer 2

Answer:

We can identify convex and concave lens without touching them by keeping any object in front of them and analysing the image form by them.

Explanation:

• When an object is between the focus and the mirror in a concave mirror, the image is virtual and therefore upright.

• When the object is beyond the focus, the image is actual and thus inverted.

• The image in a convex mirror is always fictitious and hence erect.

• Keep the object near to the mirror so that it is between the focus and the mirror.

• Move the thing away from the mirror gradually.

• The mirror is concave if the image gets inverted beyond a certain distance.

• The mirror is convex if the image does not turn inverted.

Hence, By retaining any object in front of the mirrors and analysing the image form by them we can identify convex and concave lens without touching them.

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