Archives

A student-focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle screen and the lens as under Position of candle = 12.0 cm Position of convex lens = 50.0 cm Position of the screen = 88.0 cm i) What is the focal length of the convex lens? ii) Where will the image be formed if he shifts the candle towards the lens at a position of 31.0 cm? iii) What will be the nature of the image formed if he further shifts the candle towards the lens? iv) Draw a ray diagram to show the formation of the image in case (iii) as said above.

Answer: Position of candle = 12.0 cm Position of convex lens = 50.0 cm Position of the screen = 88.0 cm (i) u = Distance of candle from... View Article

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 the 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: As the image is obtained on the screen, it is real. so, Magnification (m) = –3 v = 80 cm u =? As m = v/u so, –3 = 80/u u =... View Article

Sudha finds out that the sharp image of the window pane of her science laboratory is formed at a distance of 15 cm from the lens. She now tries to focus the building visible to her outside the window instead of the window pane without disturbing the lens. In which direction will she move the screen to obtain a sharp image of the building? What is the approximate focal length of this lens?

Answer: As the image formed is real, therefore, the lens in use is a convex lens. The distance of the real image formed by a convex lens from... View Article