(a) 25lx
(b) 11.11lx
<u>Explanation:</u>
Illuminance is inversely proportional to the square of the distance.
So,

where, k is a constant
So,
(a)
If I = 100lx and r₂ = 2r Then,

Dividing both the equation we get

When the distance is doubled then the illumination reduces by one- fourth and becomes 25lx
(b)
If I = 100lx and r₂ = 3r Then,

Dividing equation 1 and 3 we get

When the distance is tripled then the illumination reduces by one- ninth and becomes 11.11lx
100N to the left. Newton's 3rd law action and reaction
Russia and the United States sign the Moscow Treaty.
Use the formula dgh + p atm
d is density g is gravitational field strength h heigh or depth and p atm is atmospheric pressure
1000 x 10 x 20 + 100000 = 300000
almost 300,000 pascal