Answer:
540 nm
Explanation:
According to the question,
The refractive index of the soap bubble,
.
The thickness of the soap bubble wall is,
.
Now, for constructive interference of soap bubble.
.
Now for first order m=1.
Therfore,

Substitute all the variables in the above equation.
.
Therefore,
.
Therefore the visible light wavelength which is strongly reflected is 540 nm.
Question four bulbs A,B,C and D are connected in a circuit shown in the figure below, the letters X, Y and Z represent three switches. Which switch is used to operate switch A separately?
Answer: x
Answer:
if you stretch a spring with k = 2, with a force of 4N, the extension will be 2m. the work done by us here is 4x2=8J. in other words, the energy transferred to the spring is 8J. but, the stored energy in the spring equals 1/2x2x2^2=4J (which is half of the work done by us in stretching it).