Tag: ray optics and optical instruments

Quizzes (21) Questions (129)

Questions Related to ray optics and optical instruments

Multiple choice problems on prism prism ray optics and optical instruments optics physics

The refracting angle of a prism $60^{\mathrm{o}}$.The refractive index of the material of the prism is $\sqrt{\dfrac{7}{3}}$. The limiting angle of incidence of a ray that will be transmitted through the prism in this case will be :

  1. $30^{0}$
  2. $45^{\mathrm{o}}$
  3. $40^{\mathrm{o}}$
  4. $50^{\mathrm{o}}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The limiting angle of incidence is determined by the condition that the ray must be able to pass through the prism without undergoing total internal reflection at the second face.

Multiple choice image formation by lens image formation by lenses ray optics and optical instruments optics physics

If David is observing his image in plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be :

  1. 3 m

  2. 5 m

  3. 6 m

  4. 8 m
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Plane mirror produces erect image and is of same size and also at the same distance from the mirror as the object.

if he moves 1 m, distance of object from mirror= 3 m

distance of image from mirror= 3 m

distance between image and object =6 m.
Multiple choice image formation by lens image formation by lenses ray optics and optical instruments optics physics

When the reflecting or refracting rays do not actually intersect but appear to intersect when produced backwards, 

  1. a real image is formed

  2. a virtual image is formed

  3. either a real or a virtual image is formed

  4. neither a real nor a virtual image is formed
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A virtual image is formed when the refracting or reflecting rays do not actually intersect but appear to intersect when they are produced backwards.

Multiple choice image formation by lens image formation by lenses ray optics and optical instruments optics physics

Comparing real and virtual images, we may say that

  1. real images can not be obtained on a screen and virtual images can be

  2. virtual images can not be obtained on a screen and real images can be

  3. both real and virtual images can be obtained on a screen

  4. neither real nor virtual images can be obtained on a screen
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Real images can be obtained on a screen. Virtual images can not be obtained on a screen.

Multiple choice image formation by lens image formation by lenses ray optics and optical instruments optics physics

A real image is formed by

  1. actual intersection of the refracting or reflecting rays

  2. imaginary intersection of the refracting or reflecting rays produced backwards

  3. either actual or imaginary intersection of the reflecting or refracting rays

  4. neither actual nor imaginary intersection of the reflecting or refracting rays
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When the refracting or reflecting rays actually intersect, a real image is formed.

Multiple choice image formation by lens image formation by lenses ray optics and optical instruments optics physics

A thin convex lens of focal length $30.00\ cm$ forms an image $2.00\ cm$ high, of an object at infinity. A thin concave lens of focal length $20.00\ cm$ is placed $26.00\ cm$ from the convex lens on the side of the image. The height of the image now is

  1. $1.00\ cm$
  2. $1.25\ cm$
  3. $2.00\ cm$
  4. $2.50\ cm$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The convex lens forms an image at its focal point (30 cm). The concave lens is placed 26 cm from the convex lens, so the image acts as a virtual object for the concave lens at a distance of 4 cm (30 - 26 = 4 cm). Using the lens formula 1/f = 1/v - 1/u, where f = -20 and u = +4, we get 1/v = 1/-20 + 1/4 = 4/20, so v = 5 cm. Magnification m = v/u = 5/4 = 1.25. Final height = 1.25 * 2 cm = 2.50 cm.

Multiple choice image formation by lens image formation by lenses ray optics and optical instruments optics physics

A meter stick lies along the optic axis of a convex lens of focal length 40 cm its nearer end 60 cm from the mirror surface. How long is the image of stick?

  1. $200 cm$
  2. $\dfrac {200}{3} cm$
  3. $8 cm$
  4. $\dfrac{210}{6} cm$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Using the lens formula 1/f = 1/v - 1/u with f = 40 cm, the near end at u1 = -60 cm has an image distance v1 = -120 cm. The far end of the meter stick is at u2 = -160 cm, leading to an image distance v2 = -53.33 cm. The length of the image is the difference between these image positions, which evaluates to 200/3 cm.