Inverse Square Law of Light states that light intensity falls off rapidly with distance from its source. T<span>he intensity varies with the square of the flash-to-subject distance.
intensity at distance 1/intensity at distance 2=distance2^2/distance1^2
In our case, distance1=10m and distance2=20m, 20^2/10^2= 400/100=4, which means that t</span>he intensity of the wave<span> has increased by a factor of four.
Answer:D</span>
What is the unit c denotes here
Answer:

Explanation:
we know angular velocity in terms of moment of inertia and angular speed
ω .... (1)
moment of inertia of rod rotating about its center of length b
........ .(2)
using v = ωr
where w is angular velocity
and r is radius of rod which is equal to b
so we get 2v = ωb
ω = 2v/b ................. (3)
here velocity is two time because two opposite ends are moving opposite with a velocity v so net velocity will be 2v
put second and third equation in ist equation
×
so final answer will be 
Explanation:
Below is an attachment containing the solution
Answer:
15.71 m/s
Explanation:
We are given;
Time; t = 0.2 s
Radius; r = 0.5 m
The circumference will give us the distance covered.
Formula for circumference is 2πr
Thus; Distance = 2πr = 2 × π × 0.5 = π
Linear speed = distance/time = π/0.2 = 15.71 m/s