Question

A student has a convex lens with a focal length of 12 cm. How close should she put an object to the lens if she wants the image to be inverted and magnified by a factor of 3?
A. 4 cm
B. 15 cm
C. 16 cm
D. 36 cm

Answer 1

the answer is A. 4 cm

Answer 2

Here f= 12 cm (positive for convex lens)

m(magnification )=-3 (as image is real it will be inverted)

m=-(V/U) where V is image distance and U is object distance considering sign conventions

-3=-V/U

V=3U

Now using lens formula -1/U+1/V=1/f we get

-1/U+1/3U=1/12

-2/3U=1/12

U=-24/3=-8 m

So object is located at distance of 8m from the optical center of lens.

What is convex lens?

"An optical lens is generally made up of two spherical surfaces. If those surfaces are bent outwards, the lens is called a biconvex lens or simply convex lens." These types of lenses can converge a beam of light coming from outside and focus it to a point on the other side.

A convex lens is a converging lens. When parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus. The distance between the principal focus and the centre of the lens is called the focal length.

Know more about convex lens here

https://brainly.com/question/1604692

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