PDF chapter test TRY NOW
Get a square piece of cardboard of size 6-8 cm. Make two holes. Thread a string through the two holes. Draw/ paste a cage on one side of the cardboard and
a bird on the other side. Twist the string and make the card twirl rapidly. Do you see the bird in the cage?
![YCIND_230224_5053_Light_CBSE 8th_3_18.png](https://resources.cdn.yaclass.in/f369e72b-e4cc-43e4-9c5c-ed695c460747/YCIND2302245053LightCBSE8th318w300.png)
Bird in cage
, the bird in the cage .
As a result, an image's impression lasts in the retina for around of a second.