Question

A lens produces a magnification of -5. Is this a converging or diverging lens? If the focal length of the
lens is 6 cm, draw a ray diagram showing the image formation in this case
(i) A girl was playing with a thin beam of light from a laser torch by directing it from different direction on
a convex lens held vertically. She was surprised to see that in a particular direction, the beam of light
continues to move along the same direction after passing through the lens. State the reason for her
observation. Draw a ray diagram to support your answer.
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Answer 1

Explanation:

• 1) Here, Magnification is negative

• , Magnification is negativeTherefore the image is formed Inverted.

Inverted.

• Inverted. And We know that if the sign of the magnification is in negative then it will be a convex lens (Converging lens).

• 2) When the girl passed the ray of light vertically then the angle of incidence become zero because the ray of light is perpendicular to the normal and therefore there will be no any deviation occur and due to this the light ray will be passed Straightly without any refraction.

Answer 2

Explanation:

Question statement:

A girl was playing with a thin beam of light from a laser torch by directing it from different direction on  a convex lens held vertically. She was surprised to see that in a particular direction, the beam of light  continues to move along the same direction after passing through the lens. State the reason for her  observation. Draw a ray diagram to support your answer.

Solution:

• The girl must have directed the ray of light along the direction of the optical centre of the lens.
• Because the ray of light passes straight through the optical centre of the lens.