A student focuses the image of a candle flame, placed at about 2 m from a convex lens of focal length 10 cm, on a screen. After that, he moves gradually the flame towards the lens and each time its image on the screen.
(a) In which direction does he move the lens to focus the flame on the screen?
(b) What happens to the size of the image of the flame formed on the screen ?
(c ) What difference is seen in the intensity (brightnees) of the image of the flame on the screen ?
(d) What is seen on the when the flame is very close (at about 5 cm) to the lens ?

A student places a candle flame at a distance of about 60 cm from a convex lens of focal length 10 cm and focuses the umage of the flame on a screen. After that he gradually moves the flame towards the lens and each time focuses the image on the screen. (a) In which direction-toward or away from the lens, does he move the screen to focus the image ? (b) How does the size of the image change ? (c) How does the intensity of the image change as the flame moves towards the lens ? (d) Approximately for what distance between the flame and the lens, the image formed on the screen is inverted and of the same size ?

A student focuses the image of a well illuminated distant object on a screen using a convex lens. After that the gradually moves the object towards the lens and each time focuses its image on the screen by adjucting the lens. (a) In which direction -towards the screen or away from the screen, does he move the lens ? (b)What happens to the size of the image-does it decrease or increase ? (c) What happens to the image on the screen when he moves the object very close to the lens ?

To find the image - distance for varying object - distance in the case of a convex lens, a student obtains on screen a sharp image of a bright object placed very far from the lens. After that the gradually moves the object towards the lens and each time focuses its image on the screen. (a) In which direction - towards or away from the lens, does he move the screen to focus the object ? (b) What happens to the size of the image - Does it increase or decrease ? (c ) What happens when he moves the object very close to the lens ? (d) What happens to the intensity of the image as the object moves farther and farther away from the convex lens ?