Why is the efficiency of a machine always less than 100%?
1 answer:
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Answer:
(a) The potential difference between the spheres is 750 kVA
(b) The charge on the smaller sphere is 6. μC
(c) The charge on the smaller sphere, Q₁ = 13. μC
Explanation:
(a) The given parameters are;
The charge on the inner sphere, q = 5.00 μC
The radius of the inner sphere, r = 3.00 cm = 0.03 m
The charge on the larger sphere, Q = 15.0 μμC
The radius of the larger sphere, R = 6.00 cm = 0.06 m
The potential difference between two concentric spheres is given according to the following equation;
Where;
R = The radius of the larger sphere = 0.06 m
r = The radius of the inner sphere = 0.03 m
q = The charge of the inner sphere = 5.00 × 10⁻⁶ C
Q = The charge of the outer sphere = 15.00 × 10⁻⁶ C
k = 9 × 10⁹ N·m²/C²
Therefore, by plugging in the value of the variables, we have;
The potential difference between the spheres, = 750,000 N·m/C = 750 kVA
(b) When the spheres are connected with a wire, the charge, 'q', on the smaller sphere will be added to the charge, 'Q', on the larger sphere which as follows;
= Q + q = (5 + 15) × 10⁻⁶ C = 20 × 10⁻⁶ C
= 20 × 10⁻⁶ C
From which we have;
Q₁/Q₂ = R/r
Where;
Q₁ = The new charge on the on the larger sphere
Q₂ = The new charge on the on the smaller sphere
= 20 × 10⁻⁶ C = Q₁ + Q₂
∴ Q₁ = 20 × 10⁻⁶ C - Q₂ = 20 μC - Q₂
∴ (20 μC - Q₂)/Q₂ = 0.06/(0.03) = 2
20 μC - Q₂ = 2·Q₂
20 μC = 3·Q₂
Q₂ = 20 μC/3
The charge on the smaller sphere, Q₂ = 20 μC/3 = 6. μC
(c) Q₁ = 20 μC - Q₂ = 20 μC - 20 μC/3 = 40 μC/3
The charge on the smaller sphere, Q₁ = 40 μC/3 = 13. μC.
Answer:
The water level will drop by about 1.24 cm in 1 day.
Explanation:
Here Mass flux of water vapour is given as
where
is the mass flux of the water which is to be calculated.
- D is diffusion coefficient which is given as
- l is the thickness of the film which is 0.15 cm thick.
is given as
In this
is the saturated water pressure, which is look up from the saturated water property at 20°C and 0.5 saturation given as 2.34 Pa
is the air pressure which is given as 0.5 times of
- R is the universal gas constant as
- T is the temperature in Kelvin scale which is
By substituting values in the equation
Converting into
As 1 mole of water 18 so
Putting this in the equation of mass flux equation gives
For calculation of water level drop in a day, converting mass flux as
So the water level will drop by about 1.24 cm in 1 day.