Question

the focal length is 10cm if the distance is 30cm what will be image distances​

Answer 1

Answer:

$\huge\fbox\red{Answer}$

Explanation:

Using the Real Is Positive convention:

u=+30 and f=-10

1/u+1/v=1/f

1/30 + 1/v = -1/10

1/v = -1/10 - 1/30 = -3/30 - 1/30 = -4/30

v = -30/4 = -7.5 cm meaning virtual and erect. And quarter the size of the object

Answer 2

Answer:

1/f = 1/v + 1/u

=1/10 = 1/30 + 1/v

=1/v = 1/10-1/30

1/v = 2/30

1/v = 1/15

So,

v = 15