Question

The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between lens and image is \[80\,cm\] , at what distance should the candle be placed from the lens? What is the nature of the image at a distance of \[80\,cm\] and the lens?

Answer 1

Hint:To answer the question, we'll use the magnification formula to figure out what the question is. Let's start with a fundamental understanding of it. Magnification refers to the size of a picture in relation to the size of an object. Lenses and curved mirrors can be used to create magnified images.

Complete step by step answer:
The image is magnified three times and the image distance is given by: \[v = 80\,cm.\]
Now, we know that magnification is given by:
$\left( M \right) = \dfrac{v}{u}$
Now we will put the value in the above equation and find the value for $u$ ,
$3 = \dfrac{{80\,cm}}{u} \\
\Rightarrow u = \dfrac{{80cm}}{3} \\ $
Because the distance between the objects is seen as negative, and because of the sign convention,
$u = - \dfrac{{80\,cm}}{3}$
Nature of image: Because the image is created on the other side of the lens, it is both a real and an inverted image.
Nature of Lens: It is a convex lens because the enlarged image is generated by a convex lens rather than a concave lens.

Note:One thing should be noted about magnification is that magnification has no units because it is a ratio between two lengths. The image height and object height, on the other hand, should both be measured in the same units, such as centimetres \[\left( {cm} \right)\] or millimetres \[\left( {mm} \right)\] , and not a combination of the two.