Answer: 
Explanation:
Given
Wavelength of light 
Screen is
away
Distance between two adjacent bright fringe is 
When same experiment done in water, wavelength reduce to 
So, the distance between the two adjacent bright fringe is 
Keeping other factor same, distance becomes

Answer: Yes.
Explanation:
Assuming Earth and Moon are isolated is space, it is possible to have a point where Earth and Moon will pull at an object with equal force.
That point will be closer to the Moon than the Earth because Moon's gravitational field strength is weaker than Earth's gravitational field strength.
Answer:
a) 
b) 
Explanation:
Given:
- initial rotational speed of phonograph,

- final rotational speed of phonograph,

- time taken for the acceleration,

a)
Now angular acceleration:



b)
Using eq. of motion:



A) visible light because it just makes since