Question

please answer this...........

Answer 1

1.
Magnification is defined as the ratio of heights of image and object.

whereas Power is the ability of a lens to converge or diverge the light rays passing through it.

Power of a lens depends on its focal length only and it is constant.

But magnification produced by a lens is not constant. magnification can change depending on the position of the object with respect to the lens.
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2.
Power is related only to lens.

Magnification is related to both lens and mirror.
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3.
+1 magnification means image is of the same height as object and it is erect.

-1 magnification means image is of the same height as object and it is inverted.

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Another thing: Whenever image is inverted(negative magnification), image formed is real.
Whenever image is erect(positive magnification), image formed is virtual.
Please confirm with the image formation diagrams in your book(for both lens and mirror) as I am not 100% sure of all cases.
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4.
Dioptre is the unit of power of lens.

Power of convex lens is positive(as focal length is positive)
+1D means it is a convex lens with power 1D
focal length can be calculated. it is +1m

Power of concave lens is negative(as focal length is negative)
-1D means it is a concave lens with power -1D
focal length can be calculated. it is -1m
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5.
It depends on the focal length and

-- Convex lens has always positive power(because focal length is always positive)

-- Concave lens has always negative power(because focal length is always negative)

Answer 2

Hey Mate.

MAGNIFICATION:
Magnification is the ratio of image height (h2) to the object hight(h1).

Magnification is also equal to -v/u
Where v=image distance and u=object distance.

Magnification is always positive in convex mirror and always negative in concave mirror.
(note:Magnification is always negative in concave mirror except one case, when object is placed between Focus and pole then Magnifiaction becomes positive in concave mirror)

Where Magnifiaction is always negative in convex lens (except one case, when object is placed between focus and optical centre then Magnifiaction becomes positive.) and it is always positive in concave lens.

NOTE : In Lense Magnifiaction m=v/u and h2/h1..
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POWER..

Power of a lens is the ability of lens to converge or diverge the light rays after refraction..

Power always depends on Focal length. Its SI unit is Dioptre it always measure in metres(m).

Power of a lens becomes negative if focal length of lens is negative. Nd it becomes positive if focal length of lens is positive.. Thus,

Power of convex lens is always positive and power of concave lens is always negative...
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3.Yes, +1 or - 1 magnification is considered as zero magnification. (see your recently asked question on image and object distance)..
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4. As I told above that power is depends on focal length of lens. So,
+1D mean it is a convex lens and with the help of this we can find the focal length of lens with the help of power formula which is P=1/f.
Nd
-1D mean it is a concave lens and with the help of this we can find the focal length of lens with the help of power formula which is P=1/f.
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5.Read about power carefully. U will get your answer..

Hope it will helps!!!