Posts Tagged ‘optics’

Numerical Problems From Optics

  1. When an object of height 4cm is placed at 40cm from a mirror the mirror forms the image on the object itself. If the height of the image is equal to the height of the object. Find out the focal length of the mirror and identify the mirror.
  2. A convergent beam of light passes through a diverging lens of focal length 0.2m and comes to focus at distance 0.3m behind the lens.Find the position of the point at which the beam would converge in the absence of lens?

Comments - What do you think?  Posted by admin - November 15, 2011 at 4:06 pm

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A problem from Optics

A convergent beam of light passes through a diverging lens of focal length 0.2m and comes to focus at distance 0.3m behind the lens.Find the position of the point at which the beam would converge in the absence of lens?

Comments - What do you think?  Posted by admin - November 5, 2011 at 10:10 pm

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CBSE 12th Std Physics Numerical from Optics

A convex lens of crown glass(1.5) has a focal length of 15 cm. The lens is placed in (a) water(1.33) and carbon bisulphide(1,65).determine in each case whether the lens behaves as a conveging or a diverging lens and determine its focal length.

(Asked by Shobha)

Answer:

Formula used

For the lens to be converging, f must be positive and for it to be diverging, f must be negative

(a) In water the lens will be converging as the refractive index of glass is greater than that of  water.

(b) In Carbon disulphide the lens is diverging as the refractive index of glass is less than that of CS2

Comments - What do you think?  Posted by admin - September 17, 2011 at 4:45 pm

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