Question

An object is placed 12 cm in front of a diverging lens with a focal length of 7.9 cm.

(a) Find the image distance and determine whether the image is real or virtual.

(b) Find the magnification

Answer 1

Only things we need to know about this question to get answer is formula and sign convention

As for lense formula

1/v - 1/u =1/f

Where u and v are distance of object and image from centre

And f is focal length from pole(centre).

Sign convention

1..Diatance measured in the direction of falling ray are positive and oposite to it are negative.

As in diverging lens rays after reflection diverges and when retraced back creates focus on left of lense thus when measured from pole in opposite to falling ray focal length of diverging lense becomes negative.

Small (<1)magnification shows height of image wil be less then object and image distance less than focal length tell image will be form between focus and pole on left due to negative sign thus virtual image.

Thank you.