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Geometrical Optics Physics - Geometrical Optics

Bihar Board (BSEB) - STD 12 Science - Physics (BSEB - English Medium). 123 questions in this chapter.

Question types

Geometrical Optics question types

123 questions across 6 question groups — pick any mix to generate a Physics paper with step-by-step answer keys.

123
Questions
6
Question groups
5
Question types
Sample Questions

Geometrical Optics questions

One sample from each question group in this chapter. Select any group above to see the full set with answer keys.

Q 1M.C.Q [1M]1 Mark
Two concave lenses L1 and L2 are kept in contact with each other. If the space between the two lenses is filled with a material of refractive index $\mu\approx1,$ the magnitude of the focal length of the combination:
  1. Becomes undefined.
  2. Remains unchanged.
  3. Increases.
  4. Decreases.
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Q 2M.C.Q [1M]1 Mark
Two rays A and B being reflected by a mirror and going as A' and B'. The mirror:
  1. Is plane.
  2. Is convex.
  3. Is concave.
  4. May be any spherical mirror.

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Q 3M.C.Q [1M]1 Mark
Three transparent media of refractive indices $\mu_1,\mu_2$ and $\mu_3.$ A point object O is placed in the medium $\mu_2.$ If the entire medium on the right of the spherical surface has refractive index $\mu_1,$ the image forms at O'. If this entire medium has refractive index $\mu_3,$ the image forms at O". In the situation shown:
  1. The image forms between O' and O"
  2. The image forms to the left of O'
  3. The image forms to the right of O"
  4. Two images form, one at O' and the other at O".

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Q 4M.C.Q [1M]1 Mark
A point object is placed at a distance of 30cm from a convex mirror of focal length 30cm. The image will form at:
  1. Infinity.
  2. Pole.
  3. Focus.
  4. 15cm behind the mirror.
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Q 5M.C.Q [1M]1 Mark
A point object O is placed on the principal axis of a convex lens of focal length f = 20cm at a distance of 40cm to the left of it. The diameter of the lens is 10cm. An eye is placed 60cm to right of the lens and a distance h below the principal axis. The maximum value of h to see the image is:
  1. 0
  2. 2.5cm
  3. 5cm
  4. 10cm.
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Q 61 Marks Question1 Mark
A converging lens of focal length 12cm and a diverging mirror of focal length 7.5cm are placed 5.0cm apart with their principal axes coinciding. Where should an object be placed so that its image falls on itself?
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Q 91 Marks Question1 Mark
Two converging lenses of unequal focal lengths can be used to reduce the aperture of a parallel beam of light without losing the energy of the light. This increases the intensity. Describe how the converging lenses should be placed to do this.
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Q 101 Marks Question1 Mark
A thin converging lens is formed with one surface convex and the other plane. Does the position of image depend on whether the convex surface or the plane surface faces the object?
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Q 12Short Answer Type Questions [2M]2 Marks
A spherical surface of radius 30cm separates two transparent media A and B with refractive indices 1.33 and 1.48 respectively. The medium A is on the convex side of the surface. Where should a point object be placed in medium A so that the paraxial rays become parallel after refraction at the surface?
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Q 15Short Answer Type Questions [2M]2 Marks
An extended object is placed at a distance of 5.0cm from a convex lens of focal length 8.0cm.
  1. Draw the ray diagram (to the scale) to locate the image and from this, measure the distance of the image from the lens.
  2. Find the position of the image from the lens formula and see how close the drawing is to the correct result.
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Q 163 Marks Question3 Marks
A small piece of wood is floating on the surface of a 2.5m deep lake. Where does the shadow form on the bottom when the sun is just setting? Refractive index of water $=\frac{4}{3}.$
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Q 173 Marks Question3 Marks
If a piece of paper is placed at the position of a virtual image of a strong light source, will the paper burn after sufficient time? What happens if the image is real? What happens if the image is real but the source is virtual?
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Q 183 Marks Question3 Marks
The diameter of the sun is 1.4 × 109m and its distance from the earth is 1.5 × 1011m. Find the radius of the image of the sun formed by a lens of focal length 20cm.
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Q 193 Marks Question3 Marks
A light ray falling at an angle of 45° with the surface of a clean slab of ice of thickness 1m is refracted into it at an angle of 30°. Calculate the time taken by the light rays, to cross the slab. Speed of light in vacuum = 3 × 108m/s
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Q 203 Marks Question3 Marks
A concave mirror having a radius of curvature 40cm is placed in front of an illuminated point source at a distance of 30cm from it. Find the location of the image.
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Q 214 Marks Questions4 Marks
In motor vehicles, a convex mirror is attached near the driver's seat to give him the view of the traffic behind. What is the special function of this convex mirror which a plane mirror can not do?
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Q 224 Marks Questions4 Marks
A narrow pencil of parallel light is incident normally on a solid transparent sphere of radius r. What should be the refractive index if the pencil is to he focused.
  1. At the surface of the sphere.
  2. At the centre of the sphere.
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Q 234 Marks Questions4 Marks
A small object is embedded in a glass sphere $(\mu=1.5)$ of radius 5.0cm at a distance 1.5cm left to the centre. Locate the image of the object as seen by an observer standing.
  1. To the left of the sphere.
  2. To the right of the sphere.
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Q 244 Marks Questions4 Marks
A container contains water upto a height of 20cm and there is a point source at the centre of the bottom of the container. A rubber ring of radius r floats centrally on the water. The ceiling of the room is 2.0m above the water surface.
  1. Find the radius of the shadow of the ring formed on the ceiling if r = 15cm.
  2. Find the maximum value of r for which the shadow of the ring is formed on the ceiling. Refractive index of water $\frac{4}{3}.$
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Q 254 Marks Questions4 Marks
A slide projector has to project a 35mm slide (35mm × 23mm) on a 2m × 2m screen at a distance of 10m from the lens. What should be the focal length of the lens in the projector?
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Q 26Long Answer Type Questions [5M]5 Marks
A hemispherical portion of the surface of a solid glass sphere $(\mu=1.5)$ of radius r is silvered to make the inner side reflecting. An object is placed on the axis of the hemisphere at a distance 3r from the centre of the sphere. The light from the object is refracted at the unsilvered part, then reflected from the silvered part and again refracted at the unsilvered part. Locate the final image formed.
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Q 27Long Answer Type Questions [5M]5 Marks
A thin lens made of a material of refractive index $\mu_2$ has a medium of refractive index $\mu_1$ on one side and a medium of refractive index $\mu_3$ on the other side. The lens is biconvex and the two radii of curvature have equal magnitude R. A beam of light travelling parallel to the principal axis is incident on the lens. Where will the image be formed if the beam is incident from:
  1. The medium $\mu_1$
  2. From the medium $\mu_3?$
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Q 28Long Answer Type Questions [5M]5 Marks
k transparent slabs are arranged one over another. The refractive indices of the slabs are $\mu_1,\mu_2,\mu_3, \ ...\mu_{\text{k}}$ and the thicknesses are t1, t2, t3, ... tk . An object is seen through this combination with nearly perpendicular light. Find the equivalent refractive index of the system which will allow the image to be formed at the same place.
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