The images show a converging lens with focal points and an object as indicated.

Question

The images show a converging lens with focal points and an object as indicated. What kind of image is generated in each case?

Erect, real, enlarged.
Inverted, real, enlarged.
Erect, virtual, enlarged.
Inverted, virtual, enlarged.
Erect, real, reduced.
Inverted, real, reduced.
Erect, virtual, reduced.
Inverted, virtual, reduced.
No image.

Erect, real, enlarged.
Inverted, real, enlarged.
Erect, virtual, enlarged.
Inverted, virtual, enlarged.
Erect, real, reduced.
Inverted, real, reduced.
Erect, virtual, reduced.
Inverted, virtual, reduced.
No image.

If the object is moved very far away from the front of the lens, where do you expect the image?
In front of the lens, close to the focal point.
Far behind the lens.
Behind the lens, close to the focal point.
In front of the lens, close to two times the focal length.
None of the above.

I don't even understand what I'm looking at (3 parts btw)

The images show a converging lens with focal points and an object as indicated. What kind of image is generated in each case? Erect, real, enlarged. Inverted, real, enlarged. Erect, virtual, enlarged. Inverted, virtual, enlarged. Erect, real, reduced. Inverted, real, reduced. Erect, virtual, reduced. Inverted, virtual, reduced. No image. If the object is moved very far away from the front of the lens, where do you expect the image? In front of the lens, close to the focal point. Far behind the lens. Behind the lens, close to the focal point. In front of the lens, close to two times the focal length. None of the above. I don't even understand what I'm looking at (3 parts btw) Erect, real, enlarged. Inverted, real, enlarged. Erect, virtual, enlarged. Inverted, virtual, enlarged. Erect, real, reduced. Inverted, real, reduced. Erect, virtual, reduced. Inverted, virtual, reduced. No image.

Explanation / Answer

u --> object diatnce

v ---> image distance

f----> focal length

Apply, 1/u + 1/v = 1/f

1/v = 1/f - 1/u

v = f*u/(u-f)

in case 1) u > f

so, v is positive and

here, u = 1.5*f (approximately)

so, v = f*1.5*f/(1.5*f - f)

= 1.5*f/0.5

= 3*f

magnification, m = -v/u = -3*f/1.5f = -2

so, image is

inverted,real and enlarged.

in case 2) u = F

so, v = infinite

so, No image

in case 3) u = infinite

so, v = F

so, image is
Behind the lens, close to the focal point.

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