Question

Qu. 18 A glowing bulb is placed at the depth of V7 m in a
pond of water (u= 4.3) What is the minimum diameter of
an opaque circular disc placed on the surface of water so
that the bulb is not visible.
(a) 2m
(b) 3m
(c) 4m
(d) 6m​

Answer 1

Answer:

Explanation:

R=hμ2−1−−−−−√=27–√(43)2−1−−−−−−−√

=27–√7√3=6cm

Diameter of disc =2R=12cm

R=12/2

R=6cm