We see black colour in absence of light. Black colour absoorbs all the light, ( just opposite of white) and hence we do not see any colour. Black colour is also related to darkness.
Answer:
Answer for A
Explanation:
F1=GmM/r1^2
If r2 becomes r2=5r
F2=GmM/(25r^2)
Multiply with 25 gives to maintain the same force
I.e.,25F2=F1
F2=G(25m)M/25r^2=F1
By the factor 25 would change to increase to same.
Answer:
Part a)

Part B)

Part C)

Explanation:
Part a)
Magnetic field due to a long ideal solenoid is given by

n = number of turns per unit length



now we know that magnetic field due to solenoid is


Now magnetic flux due to this magnetic field is given by




Part B)
Now for mutual inductance we know that




now we have


Part C)
As we know that induced EMF is given as



The correct answer to go in the blank would be A) The particles are moving faster.
Answer:
The formation of a rainbow is more a demonstration of the wave-like behavior of light.
Explanation:
A rainbow is caused by the interaction of sunlight with atmospheric conditions. A rainbow formation results from the refraction and reflection of light due to changes in the light's wavelength direction. Naturally, light enters a water droplet, slowing down and bending as it goes from air to denser water in a refraction as if "bent." Then light reflects off the inside of the droplet, separating into its component wavelengths or colors. With light exiting from the droplet, a rainbow is formed.