Question

the focal length of a shperical mirror with a radius of curvature 30cm is

1. 30cm
2. 60cm
3. 15cm
4. 45cm​

Answer 1

Answer:

f=15cm

Explanation:

focal length=radius/2

f=30/2

f=15cm

Answer 2

Question:

The focal length of a spherical mirror with a radius of curvature 30cm is?

Answer:

The answer for your question is Option-3:

$\mapsto\bf{15cm}$

Explanation:

Before moving on to the problem, it is necessary to know two terms:

Radius of curvature:

•Radius of the curvature is the distance or length from center of curvature and pole of the spherical mirror.

•Usually, it is denoted by the letter, 'R'

Focal length:

•Focal length is the distance or length from Principal focus to the pile of the spherical mirror.

•Usually, it is denoted by the letter, 'f'

Note: Focal length is not denoted as F(capital) since, F is denoted by the Principal Focus

Now, there is a relation between radius of curvature and focal length:

$\bf{\mapsto\;\;\orange{R = 2f}}$

$\bf{\mapsto\;\;\boxed{\orange{\bf{f = \dfrac{R}{2}}}}}$

Let us apply this formula to find the focal length of the spherical mirror.

$\leadsto\sf{f = \dfrac{30}{2}}$

$\bf{\mapsto\;\;{\underline{\underline{\red{f = 15cm}}}}}\checkmark$

$\sf{\therefore \:Option-3(Focal\:length = 15cm) is\:the\:answer}$