Answer:
Option (c) is correct.
Explanation:
The apparent change in the frequency of light due to the relative motion between the source and the observer is called Doppler's effect.
When the source is moving towards the observer which is at rest, the apparent frequency increases and if the observer is moving away the frequency of sound decreases.
It occurs for both light and sound.
So, to explain the blue shift of light in the universe is due to the Doppler's effect of light.
Answer:
1:2
Explanation:
It is given that,
Initial RMS AC voltage is 100 V and final RMS AC voltage is 200 V.
We need to find the ratio of the number of turns in the primary to the secondary for step up transformer.
For a transformer, 
So,

So, the ratio of the number of turns in the primary to the secondary is 1:2.
Answer:

Explanation:
The angular acceleration is:


And the angular deceleration is:


The total number of revolutions is:



Answer:
The difference between rotations and revolutions is , when an object turns around an internal axis (like the Earth turns around its axis) it is called a rotation. When an object circles an external axis (like the Earth circles the sun) it is called a revolution.
Explanation:
While rotation means spinning around its own axis, revolution means to move around another object. Taking the example of the Earth, which rotates 366 times to complete one revolution around the Sun.
If gravity did not affect the path of a horizontally thrown ball the ball would eventually slow due to air resistance. If the ball were somehow thrown in a vacuum devoid of gravity and air, it would technically continue in a straight line forever.