Question

A convex lons has radii 40 cm and 60 cm. The 40 cm surface is silvered The effective focal
length of the mirror so formed is (Take refractive index=3/2)
(a)-12 cm
(b)-11 cm
(c)-10 cm
(d) 9 cm
​

Answer 1

Answer:

The first few prime numbers are: 2, 3, 5, 7, 11, 13, 17, 19 and 23, and we have a prime number chart if you need more.

If we can make it by multiplying other whole numbers it is a Composite Number.

Like this:

prime composite

2 is Prime, 3 is Prime, 4 is Composite (=2×2), 5 is Prime, and so on...