Question

the radius o curvature of a spherical mirror is 20cm.what is its focal length
?

Answer 1

Since focal length = 1/2 × Radius of curvature
therefore, f = 1/2 × 20 = 10cm

Answer 2

Answer :

• $\boxed{\textsf{\textbf{Focal length = 10 cm}}}$

Given :

• Radius of curvature of a spherical mirror (R) = 20 cm

To Find :

• Focal length (f) = ?

Explanation:

Formula used :

$\boxed{\boxed{ \bold{\sf Focal \ length \ (f) = \frac{Radius \ of \ curvature \ (R)}{2}}}}$

Substituting value of R in the equation we get :

$:\implies \sf Focal \: Length \: (f)= \dfrac{20}{2}$

$:\implies \sf Focal \: Length \: (f)= \dfrac{ \cancel{2 }\times 10}{ \cancel{2}}$

$:\implies \underline{ \boxed{\sf Focal \: Length \: (f)= 10 \: cm}}$

Therefore, Focal Length (f) = 10 cm