1)An object of height 4 cm is placed at a distance of 20 cm from a convex lens of focal length 10 cm. Find the nature of the image.

1/f=1/d1+1/do
d1=fdo/do-f
(10)(20)/20-10
d1=20

m=-(20)(4)/20
-4 or 4 away
answer: real, inverted

2)Light passes from air into water at 45.0 d/C to the normal. If the index of refraction of water is 1.33, find the angle of refraction.

sin-1((1.00/1.33)sin45.0
32.1 d/C

1 answer

The numbers are correct, but I am not familiar with your "d/C" notation. I hope it has nothing to do with degrees C, which is a unit of temperature, not angle. Angle-measuring units are just called "degrees".