Question

What is the focal length of a concave mirror
whose radius of curvature is 20 cm?
15 cm
0 40 cm
@ 20 cm
© 10 cm​

Answer 1

Answer:

The focal length of mirror is 10 cm

Explanation :-

The radius of curvature of a mirror is 20 cm.

so,

f = R/2

=20/2 =10cm

so,the focal length will be be 10cm

Answer 2

$\huge{\underline{\boxed{\mathbb{\color{pink}QUESTION}}}}$

What is the focal length of a concave mirror

whose radius of curvature is 20 cm?

$\huge\underline\mathtt\color{green}Given:$

The radius of curvature(r)= 20 cm.

$\huge\underline\mathtt\color{green}To \: find:$

The focal length of a concave mirror(f)=?

$\rule{300}{2}$

$\huge{\underline{\boxed{\mathbb{\color{pink}SOLUTION}}}}$

As we know,

$r = 2f \\ \implies f = \frac{r}{2} \\ \implies \: f = \frac{20}{2} \\ \implies f = 10$

$\mathtt\green{Hence, \: the \: focal \: length \: of \: the \ } \\ \mathtt\green{concave \: mirror \: is \: 10cm.}$