Optical instruments and the eye
Answers are for parents and teachers.
1
How many times does a magnifier with F = 2 cm magnify (D₀ = 25 cm)?
12.5
2
Telescope: F_obj = 90 cm, F_eye = 3 cm. Find K.
30
3
Microscope: F₁ = 0.4 cm, F₂ = 2 cm, l = 16 cm. K ≈ ? (D₀ = 25 cm)
K ≈ 16·25/(0.4·2) = 500
4
A person who cannot see beyond 40 cm needs spectacles of what optical power? (with sign)
D = –1/0.4 = –2.5 dptr
5
Why is it dangerous to look at the Sun through a telescope or binoculars?
The lens concentrates the light on the retina and burns it.