Question

A concave mirror is placed facing the sun. where does the sun rays get converged
a) at centre of curvature
b) at pole of the mirror
c) a and b
d) at focus​

Answer 1

$\LARGE{ \underline{ \purple{ \sf{Required \: answer:}}}}$

When light rays coming from infinity to a concave mirror, the image is formed at the focus. This point is better known as Optical focus.

• If the rays are not parallel to the principal axis, then the image is diminished, real & inverted.

• But if the rays are parallel to the principal axis, then the image is highly diminished, real & inverted.

Hence, the correct option is D (at focus)

━━━━━━━━━━━━━━━━━━━━

Let's see, where the image is formed according to the position of object in Concave mirror.

• At infinity - At focus
• Between Infinity and C - Between C and F
• At C - At C
• Between F and C - Beyond C
• At F - Infinity
• Between F and P - Behind the mirror.

Answer 2

TO FIND ;-

• Where does the sun's rays get converged .

GIVEN ;-

• A concave mirror is placed facing the sun .

REASON ;-

✯ It means that the sun is acting as object for the Concave mirror .

✯ And we know that sun is placed at infinity from the mirror .

$\huge{\color{aqua}\checkmark}$ $\bf\red{Object\:Distance\:(u)\:=\:\infty\:}$

We know that,

• When an object placed at infinity infront of a concave mirror, the image is formed $\bf{\pink{\underline{\underline{\blue{at\:Focus\:(f)\:}}}}}$ .

• And the nature of the image is $\bf\green{Real\:,\:inverted\:\&\:highly\:diminished\:.}$

$\bf\orange{:\implies\:\left|\:m\:\right|\:<\:<\:1\:\:\:\:\&\:\:\:\:m\:<\:0\:}$

☞ See the attachment diagram .

$\huge\red\therefore$ d) At focus .