Class 12 Physics

Ashok0210

Asked: March 21, 2021In: Class 12 Physics

Figure shows an equiconvex lens (of refractive index 1.50) in contact with a liquid layer on top of a plane mirror. A small needle with its tip on the principal axis is moved along the axis until its inverted image is found at the position of the needle. The distance of the needle from the lens is measured to be 45.0 cm. The liquid is removed and the experiment is repeated. The new distance is measured to be 30.0 cm. What is the refractive index of the liquid?

$Figure shows an equiconvex lens (of refractive index 1.50) in contact with a liquid layer on top of a plane mirror. A small needle with its tip on the principal axis is moved along the axis until its inverted image is found at the position of the needle. The distance of the needle from the lens is measured to be 45.0 cm. The liquid is removed and the experiment is repeated. The new distance is measured to be 30.0 cm. What is the refractive index of the liquid?$

Class 12 Physics CBSE and UP Board Ray Optics and Optical Instruments Chapter-9 Exercise 9.38 NCERT Solutions for Class 12 Physics Chapter 9 Question-38

Ashok0210

Asked: March 21, 2021In: Class 12 Physics

Light incident normally on a plane mirror attached to a galvanometer coil retraces backwards as shown in Figure. A current in the coil produces a deflection of 3.5° of the mirror. What is the displacement of the reflected spot of light on a screen placed 1.5 m away?

Class 12 Physics CBSE and UP Board Ray Optics and Optical Instruments Chapter-9 Exercise 9.37 NCERT Solutions for Class 12 Physics Chapter 9 Question-37

Ashok0210

Asked: March 21, 2021In: Class 12 Physics

A Cassegrain telescope uses two mirrors as shown in Figure.9.33 Such a telescope is built with the mirrors 20 mm apart. If the radius of curvature of the large mirror is 220 mm and the small mirror is 140 mm, where will the final image of an object at infinity be?

Class 12 Physics CBSE and UP Board Ray Optics and Optical Instruments Chapter-9 Exercise 9.36 NCERT Solutions for Class 12 Physics Chapter 9 Question-36

Ashok0210

Asked: March 21, 2021In: Class 12 Physics

(a) For the telescope described in Exercise 9.34 (a), what is the separation between the objective lens and the eyepiece? (b) If this telescope is used to view a 100 m tall tower 3 km away, what is the height of the image of the tower formed by the objective lens? (c) What is the height of the final image of the tower if it is formed at 25 cm?

Class 12 Physics CBSE and UP Board Ray Optics and Optical Instruments Chapter-9 Exercise 9.34 NCERT Solutions for Class 12 Physics Chapter 9 Question-34

Ashok0210

Asked: March 21, 2021In: Class 12 Physics

A small telescope has an objective lens of focal length 140 cm and an eyepiece of focal length 5.0 cm. What is the magnifying power of the telescope for viewing distant objects when (a) the telescope is in normal adjustment (i.e., when the final image is at infinity)? (b) the final image is formed at the least distance of distinct vision (25 cm)?

Class 12 Physics CBSE and UP Board Ray Optics and Optical Instruments Chapter-9 Exercise 9.34 NCERT Solutions for Class 12 Physics Chapter 9 Question-34

Ashok0210

Asked: March 21, 2021In: Class 12 Physics

An angular magnification (magnifying power) of 30X is desired using an objective of focal length 1.25 cm and an eyepiece of focal length 5 cm. How will you set up the compound microscope?

Class 12 Physics CBSE and UP Board Ray Optics and Optical Instruments Chapter-9 Exercise 9.33 NCERT Solutions for Class 12 Physics Chapter 9 Question-33

Ashok0210

Asked: March 21, 2021In: Class 12 Physics

Answer the following questions: (a) The angle subtended at the eye by an object is equal to the angle subtended at the eye by the virtual image produced by a magnifying glass. In what sense then does a magnifying glass provide angular magnification? (b) In viewing through a magnifying glass, one usually positions one’s eyes very close to the lens. Does angular magnification change if the eye is moved back? (c) Magnifying power of a simple microscope is inversely proportional to the focal length of the lens. What then stops us from using a convex lens of smaller and smaller focal length and achieving greater and greater magnifying power? (d) Why must both the objective and the eyepiece of a compound microscope have short focal lengths? (e) When viewing through a compound microscope, our eyes should be positioned not on the eyepiece but a short distance away from it for best viewing. Why? How much should be that short distance between the eye and eyepiece?

Class 12 Physics CBSE and UP Board Ray Optics and Optical Instruments Chapter-9 Exercise 9.32 NCERT Solutions for Class 12 Physics Chapter 9 Question-32

Ashok0210

Asked: March 21, 2021In: Class 12 Physics

What should be the distance between the object in Exercise 9.30 and the magnifying glass if the virtual image of each square in the figure is to have an area of 6.25 mm²? Would you be able to see the squares distinctly with your eyes very close to the magnifier? [Note: Exercises 9.29 to 9.31 will help you clearly understand the difference between magnification in absolute size and the angular magnification (or magnifying power) of an instrument.]

Class 12 Physics CBSE and UP Board Ray Optics and Optical Instruments Chapter-9 Exercise 9.31 NCERT Solutions for Class 12 Physics Chapter 9 Question-31

Ashok0210

Asked: March 21, 2021In: Class 12 Physics

(a) At what distance should the lens be held from the figure in Exercise 9.29 in order to view the squares distinctly with the maximum possible magnifying power? (b) What is the magnification in this case? (c) Is the magnification equal to the magnifying power in this case? Explain.

Class 12 Physics CBSE and UP Board Ray Optics and Optical Instruments Chapter-9 Exercise 9.30 NCERT Solutions for Class 12 Physics Chapter 9 Question-30

Ashok0210

Asked: March 21, 2021In: Class 12 Physics

A card sheet divided into squares each of size 1 mm2 is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 9 cm) held close to the eye. (a) What is the magnification produced by the lens? How much is the area of each square in the virtual image? (b) What is the angular magnification (magnifying power) of the lens? (c) Is the magnification in (a) equal to the magnifying power in (b)? Explain.

Class 12 Physics CBSE and UP Board Ray Optics and Optical Instruments Chapter-9 Exercise 9.29 NCERT Solutions for Class 12 Physics Chapter 9 Question-29

Category: Class 12 Physics

Light incident normally on a plane mirror attached to a galvanometer coil retraces backwards as shown in Figure. A current in the coil produces a deflection of 3.5° of the mirror. What is the displacement of the reflected spot of light on a screen placed 1.5 m away?

A Cassegrain telescope uses two mirrors as shown in Figure.9.33 Such a telescope is built with the mirrors 20 mm apart. If the radius of curvature of the large mirror is 220 mm and the small mirror is 140 mm, where will the final image of an object at infinity be?

An angular magnification (magnifying power) of 30X is desired using an objective of focal length 1.25 cm and an eyepiece of focal length 5 cm. How will you set up the compound microscope?

(a) At what distance should the lens be held from the figure in Exercise 9.29 in order to view the squares distinctly with the maximum possible magnifying power? (b) What is the magnification in this case? (c) Is the magnification equal to the magnifying power in this case? Explain.

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