March 3, 2014

10th Physics New Text Book - Activity 1 from Reflections of Light

Formation of image in pinhole camera: You might have remember, that how an image forms in a pinhole camera that you have learnt in class 6. Draw a ray diagram of formation of an image in pinhole camera.

Think, what happens if we increase the size of the hole of pinhole camera. Observe the flame of a candle with pinhole camera making a big hole to it. Try to draw a ray diagram for the formation of image in a pinhole camera with a big hole. Look at figure 1.

By observing the figure we can understand that the light rays coming from the top of the candle flame fall at different points on the screen. Similarly the rays coming from bottom of the candle flame also fall at different points on the screen. Thus we get blurred image on the screen due to the big hole of the camera as shown figure 1.

Think and discuss

• Does the explanation match with your observation?
• What happens if the hole is much bigger i.e. equal to the size of the flame?
• If it is so, can we get the image of flame on the screen of pinhole camera? Why?
• What happens if we observe the same flame with the same pinhole camera from a far distance?
Think and say. Do the experiment and check your answer.

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