If the image formed by a lens for all positions of the object placed in front of it is always virtual, erect and diminished, state the type of the lens. Draw a ray diagram in support of your answer. If the numerical value of focal length of such a lens is 20cm, find its power in new cartesian sign conventions.
CBSE FOREIGN - SET 1 2016
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Diverging lens/ concave lens
We know that, $\text{P}=\frac{1}{\text{f meter}}$
When we convert 20cm into meter, we get 0.2m
Therefore, $\text{P}=\frac{1}{0.2 \text{ meter}}$
or, P = 5m
We know that, $\text{P}=\frac{1}{\text{f meter}}$
When we convert 20cm into meter, we get 0.2m
Therefore, $\text{P}=\frac{1}{0.2 \text{ meter}}$
or, P = 5m
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