Question

a concave lens of focal length 15 cm and image 10 cm from the lens how far the object is from the lens from the lens draw the ray diagram...


plz answer me fast and answer correctly​

Answer 1

Answer:

Given,

focal length, f = -15 cm

Distance of image, v = -10 cm

Distance of object, u =?

We know that,

1/v - 1/u = 1/f

So,

1/-10 - 1/u = 1/-15

So, -1/10 + 1/15 = 1/u

(-3 + 2)/30 = 1/u

-1/30 = 1/u

Therefore u = -30 cm

Thus object is placed 30 cm away from the concave lens.

Negative sign shows that object is at 30cm in front of the lens.

Answer 2

Answer:

-6

Explanation:

1/v_1/u =1/f its lenses formula

1/v=1/10 1/f=1/15

our focal length will be negative as it's a concave lense

1/u=1/-15 - 1/10

10-(-15)/-150

25/-150

1/u=-1/6

u=-6

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