A double convex lens of focal length 15 cm is used as a magnifying gla – InterviewSolution

InterviewSolution

1.	A double convex lens of focal length 15 cm is used as a magnifying glass in order to produce an erect image which is 3 times magnified. What is the distance between the object and the lens ?
Answer» f = 15 cm m = 3 Magnifying power `(m)=(-upsilon)/(u)=(f)/(f-u)` `3=(15)/(15-u)` `45-3u=15` `3u=45-15` `3u=30` `u=(30)/(3)=10cm.`

Discussion

No Comment Found

Related InterviewSolutions

A 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of the image and the magnification.
An object is placed at a distance of 20 cm from a thin double convex lens of focal length 15 cm. Find the position and magnification of the image.
d) Does the apparent depth of a tank of water change if viewed obliquely? If so, does the apparent depth increase or decrease ?
A small bulb is placed at the bottom of a tank containing water to a depth of 80 cm. What is the area of the surface of water through which light from the bulb can emerge out ? Refractive index of water is 1.33. (Consider the bulb to be a point source.)
c) The above person prefers to remove his spectacles while reading a book. Explain why ?
The far point of a myopic person is 80 cm in front of the eye . What is the natuure and power of the lens required to correct the defect ?
a) Figure shows a cross - section of a light pipe made of a glass fibre of refractive inde 1.68. The outer covering of the pipe is made of a material of refracitive index 1.44. What is the range of the angles of the incident rays with the axis of the pipe for which total reflections inside the pipe take place, as shown in the figures. b) What is the answer if there is no outer covering of the pipe?
Define power of a lens and write its unit
What are the laws of reflection through curved mirrors ?
What is optical density and how is it different from mass density ?