Question

1. An object is put at a distance of 5 cm from the
first focus of a convex lens of focal length 10cm.
If a real image is formed it's distance from the
lens will be :-
(1) 15 cm
(2) 20 cm
(3) 25 cm
(4) 30 cm



pls do full calculation​

Answer 1

HEYA GM ❤

★ FROM DISTANCES FROM FOCUS ;

» WE USE NEWTON'S FORMULA ::::::

→ X¹ = Distance of Object from first Focus

→ F = Focal length of the Mirror

→ X² = Distance of " Image " from second focus

★ Now ;

≈ NEWTON'S FORMULA = { F = √ X¹ × X² }

» F = √ X¹ × X²

» 10² = X¹ × X²

» 100 = 5 × X²

» X² = 100 / 5 = 20

«★» Hence Distance Of " Image " From second Focus is " 20cm"

★ BUT DISTANCE FROM LENS IS ;

» 20( Distance from Second Focus) + 10 ( Focal length) = 30 cm ( Image distance)

★★★ HENCE ; IMAGE DISTANCE FROM MIRROR IS " 30cm".

ANSWER :- OPTION D ≈ 30 CM .

TQ ❤ ❤

Answer 2

Answer:

Option D

⇒ 30 cm.

Explanation:

Given :-

Object Distance = 5 cm

Focal Length = 10 cm

To Find :-

Distance from lens.

Formula to be used :-

Newton's Formula = F = $\sqrt{x^1.x^2}$

Solution :-

⇒ $\sqrt{x^1.x^2}$

⇒ 10² = X¹ × X²

⇒ 100 = 5 × X²

⇒ X² = 100 / 5 = 20

Distance of Image from 2nd focus  is 20 cm.

We have to find the Distance from lens,

Distance from lens = Distance from Second Focus + Focal length

Distance from lens = (20 + 10) cm

Distance from lens = 30 cm

Hence, Distance from lens is 30 cm.