Question

an object 3cm height is placed at a distance of 15cm from a concave mirror (R=20cm) then find the nature ,position of the image ?
note:-you dont know 'f' value here so find 'f' value and then 'v' value and finally 'm'=?​

Answer 1

Answer:

Given that,

Height h=3cm

Distance u=−15cm

Radius = 10cm

Now, the focus

f=

2

r

f=

2

10

=5cm

Now, by using mirror equation

f

1

=

v

1

+

u

1

5

1

=

v

1

−

15

1

v

1

=

5

1

+

15

1

v=

4

15

cm

v=4cm

So, the image will be formed between focus and pole

Now, the magnification is

m=

u

−v

m=

15

4

Now,

m=

h

h

′

15

4

=

3

h

′

h

′

=

15

12

h

′

=0.8

Hence, the height of image is 0.8 cm and distance of image is 4 cm

Answer 2

Answer:

Image is formed behind the mirror

image formed is virtual and erect.

explaination is given in the image on the top.