Name: Total Internal Reflection From Prism
Uploaded: 2019-07-19
Duration: 1 min 56 s
Description: You must have seen reflectors on a bicycle. Why are they attached to the mudguards? What use do they have? Let’s watch this video on reflectors to find out.

Question

Draw a labelled ray diagram of compound microscope and derive the expression for magnifying power. When the final image is formed at least distance of distinct vision

D

. What will be the length of the microscope tube in this case?

Accepted Answer

(a) Labelled diagram of compound microscope. The objective lens form image A' B' near the first focal point of eyepiece.

Angular magnification of objective lens $m_{0}$ = linear magnification h'/h

$tanβ = \frac{h'}{h} = \frac{L}{f_{0}} m_{0} = \frac{h'}{h} = \frac{L}{f_{0}} . . . . . . . . . . . . (1)$

Where L is the distance between second focal point of the objective and first focal point of eyepiece. If the final image A'' B'' is formed at the near point.

Angular magnification $m_{e} = (1 + \frac{D}{f_{e}})$

If the final image A'' B'' is formed at infinity, then angular magnification $m_{e} = D / f_{e}$ ............(2)

Thus, total magnification of the compound microscope

$M = m_{0} \times m_{e} = L / f_{0} x D / f_{e}$

Aperture and focal length increase or decrease the resolving power of the compound microscope. Resolving power of microscope is given by

$R . P . = (2 n \sin θ) / (1.22 λ)$

On decreasing the aperture (diameter) of the objective lens, value of sin q decreases, and hence resolving power decreases.On decreasing the focal length of the objective lens, value of sin q increases and hence resolving power increases.

The objective lens produces a real, inverted image and the eyepiece acts as a simple magnifier and does not re-invert and produces a virtual image. So overall the image is inverted and virtual.

Tube length,

$L = v + u_{e} L = (\frac{{uf}_{0}}{u - f_{0}} + \frac{{Df}_{e}}{D + f_{e}})$

Draw a labelled ray diagram of compound microscope and derive the expression for magnifying power. When the final image is formed at least distance of distinct vision $D$ . What will be the length of the microscope tube in this case?

Important Questions on Ray Optics and Optical Instruments

Learn and Prepare for any exam you want !

Draw a labelled ray diagram of compound microscope and derive the expression for magnifying power. When the final image is formed at least distance of distinct vision D. What will be the length of the microscope tube in this case?

Important Questions on Ray Optics and Optical Instruments

Learn and Prepare for any exam you want !

Draw a labelled ray diagram of compound microscope and derive the expression for magnifying power. When the final image is formed at least distance of distinct vision $D$ . What will be the length of the microscope tube in this case?