(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
The Cosmic Ray is a natural way for nuclear fission and nucleosynthesis to occur. It refers to the formation of chemical elements from the impact of cosmic rays on an object.
Radio wave only would be the answer.
Answer:
Both warming up and cooling down or not important
Answer:
Current, I = 3.57A
Explanation:
A current of I amperes means that I Coulombs of charge flows through the conductor (heating coil) per second.
Therefore, in time t, the total charge (Q) passing through any point in which the current (C) flows will be given by the equation;
Q = It
Where; Q is the charge in coulombs; I is the current in amperes; t is the time in seconds.
From the question, we were given the following parameters;
Q = 25C, t= 7secs and I =?
From the equation, Q = It
We make current, I the subject of formula;
Thus, I = Q/t
Substituting into the equation;
I = 25/7
I = 3.57Amp.