Question

(b) A person needs a lens of power + 2.5 dioptres for correcting his vision. Name the defect of vision
he is suffering from. Which type of lens will he be using for the correcting the defect? Also find
the focal length of lens.
Explain the functioning of guard cells in leaves of plant.​

Answer 1

Answer:

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➡ Since positive sign indicate that Coverging lens so the defect is Hypermetropia. He would prefer Convex lens and focal length is 0.4 m.

➡Guard cells help in :-

• Transpiration.
• Opening and closing of stomata.

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Answer 2

Explanation:

He is suffering from hypermetropia , because the focal length is positive .

Lens used is convex lens.

So focal length is

P = 1/F (in metre)

+2.5 = 1/F

F = 1/ 2.5

F = 0.4 metre or 40 cm

Functions of guard cell ÷

1. Guard cells help in closing and opening of stomata.
2. It helps in exchange of gases.

Thank you