# Physics GK 19 - Light and Human Eye

1. Which of the following is the mirror formula?
[A] v + u =f
[B] 1/v + 1/u = 1/f
[C] 1/v + 1/u = f
[D] None of the above

2. What do we call the phenomenon of light being deflected when travelling obliquely from one medium to another?
[A] Refraction
[B] Reflection
[C] Dispersion
[D] Convergence

3. Which of the following represents the Snell’s law?
[A] sine of angle of incidence/sine of angle of refraction = constant
[B] cosine of angle of incidence/cosine of angle of refraction = constant
[C] tangent of angle of incidence/tangent of angle of refraction = constant
[D] angle of incidence – angle of refraction = constant

4. What is the refractive index of water?
[A] 1
[B] 1.01
[C] 1.33
[D] 1.78

5. What happens when light travels from a denser medium to a rarer medium?
[A] it slows down and bends towards the normal
[B] it speeds up and bends towards the normal
[C] it slows down and bends away from the normal
[D] it speeds up and bends away from the normal

6. Where will be the image formed by a convex lens when the object is placed at the focus?
[A] No image is formed
[B] At focus
[C] Between focus and optical centre
[D] At infinity

7. Which of the following gives the power of a lens?
[A] equal to its focal length
[B] reciprocal of its focal length
[C] half of its focal length
[D] double the focal length

8. Which of the following is true about a concave lens?
[A] power of a concave lens is positive
[B] power of a concave lens is negative
[C] power of a concave lens is zero
[D] None of the above

9. What is the S.I. unit of power of a lens?
[A] metre
[B] watt
[C] dioptre
[D] second