The type of heat that the Sun emits is called UV (Ultra Violet) rays. This is a natural type of heat, but it can also be dangerous if you expose yourself to too much UV heat, causing "sunburns", or even skin cancer.
Efficiency η is the ratio of input work over the output work. It is defined as:
η=work done/heat absorbed=(Q₂-Q₁)/Q₁ where Q₁ is the heat absorbed and Q₂-Q₁ is the work done.
This ratio is never greater or equal to 1, or 100% because the second law of thermodynamics doesn't allow it.
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Answer:
a) q = 7.5 10⁻² C
, b) 190 J
, c) I₀ = 50 A
, d) 1.5 mC
Explanation:
The expression for capacitance is
C = q / DV
q = C DV
let's reduce the magnitudes to the SI system
ΔV = 5 kV = 5000 V
C = 15 μF = 15 10⁻⁶ F
t = 90 μs = 90 10⁻⁶ s
q = 15 10⁻⁶ 5000
q = 7.5 10⁻² C
b) the energy in a capacitor is
U = ½ C ΔV²
U = ½ 15 10⁻⁶ 5000²
U = 1,875 10² J
answer 190 J
c) At the moment the discharge begins, all the current is available and it decreases with time,
whereby
V = I R
in the first instant I = Io
I₀ = V / R
I₀ = 5000/100
I₀ = 50 A
but this is for a very short time
answer 50 A
d) The definition of current is
i = dq / dt
in this case they give us the total current and the total time, so we can find the total charge
i = q / t
q = i t
q = 17 90 10⁻⁶
q = 1.53 10⁻³ C
answer is 1.5 mC
The correct answer is:
false
The explanation:
It is not called a control group as the control group is a group of subjects closely resembling the treatment group in many demographic variables but not receiving the active medication or factor under study and thereby serving as a comparison group when treatment results are evaluated.
