A spider is hanging by means of its own silk thread directly

Last updated: 6/3/2023

A spider is hanging by means of its own silk thread directly above a transparent fixed sphere of radius R 20 cm as shown in the figure The refractive index of the material of the sphere is equal to 2 and the height of the spider from the centre of the sphere is 2R 40 cm An insect initially sitting at the bottom starts crawling on the sphere along a vertical circular path with the constant speed of 4 cm s For how long time the insect will be invisible for the spider assume that it crawls once round the vertical circle A 80 sec 160 C sec 3 B 320 3 80 3 sec sec spide