. 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 focuses 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 (brightness) of the image of the flame on the screen? (d) What is seen on the screen when the flame is very close (at about 5 cm) to the lens?
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4
a)The object is being moved towards the lens(as the stated in the question)
b)The size of the image increases as we move closer to the lens.
c)The brightness of the image also increases as the image gets more focused to a point.
d)When it gets to a distance of 5cm from the lens it is closer than the focal length and therefore we get a virtual image which cannot be caught on a screen
b)The size of the image increases as we move closer to the lens.
c)The brightness of the image also increases as the image gets more focused to a point.
d)When it gets to a distance of 5cm from the lens it is closer than the focal length and therefore we get a virtual image which cannot be caught on a screen
Amily:
are you sure about the brightness that it will also get increased?
Sorry I am not sure about it.
plss get it sure for me plzz
The answer was wrong.In a convex lens when the object is at infinity the image is formed at the focal length and is hence point sized having maximum brightness/intensity.As we move closer towards the lens the brightness decreases(does not increase as mentioned in my previous answer)
Answered by
5
a. He should move lens away from screen because as object distance decreases image will go away from the focus.
b. Size of image will increase as the object is moved towards lens.
c. As image is magnifying intensity of flame decreases.
d. No will be formed on screen as it will form virtual image the the case.
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