You are provided with two lenses of focal length 20cm and 30cm, respectively. Which lens will you use to obtain more convergent light?
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Focal length of the first lens, $\text{F}_1=20\text{cm}$ Focal length of the other lens, $\text{F}_2=30\text{cm}$ We know that power of the lens is given by:$\text{P}=\frac{1}{\text{F}}$
Focal length of any lens is the point where light converges. So, if focal length is more then the lens has converged the light to a larger distance that is it has converged less. Whereas, if the focal length is less then the light is converged at a smaller distance that is converged more. So, we can affirm that lens of 20cm should be used to converge light to a larger extent.
Focal length of any lens is the point where light converges. So, if focal length is more then the lens has converged the light to a larger distance that is it has converged less. Whereas, if the focal length is less then the light is converged at a smaller distance that is converged more. So, we can affirm that lens of 20cm should be used to converge light to a larger extent.
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