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2 answers:
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Answer:
The power decreases by 36%
Explanation:
Given:
At 20° C
Power, P₀ = 300 W
Potential difference, V = 150 volts
Now, power is given as
P = V²/R
where, R is the resistance
on substituting the values, we get
300 = 150²/R₀
or
R₀ = 75 Ω
Now, the variation of resistance with temperature is given as
R = R₀[1 + α(T - T₀)]
where, α is the temperature coefficient of resistivity = 0.0003125 (°C⁻¹)
now, at
T₀ = 20° C
R₀ = 75 Ω
for
T = 1820° C
we have
R = R₀[1 + α(T - T₀)]
substituting the values
we get
R = 75×[1 + 0.0003125 × (1820 - 20)]
or
R = 117.18 Ω
Now using the formula for power
We have,
P = V²/R
or
P = 150²/117.18 = 192 W
Therefore, the percentage change will be
=
on substituting the values , we get
=
= -36%
here, negative sign depicts the decrease in power
Answer:
thinnest soap film is 206.76 nm
Explanation:
Given data
wavelength = 550 nm
index of refraction n = 1.33
to find out
What is the thinnest soap film
solution
we have wavelength λ = 550 nm
that is λ = 550 × m
and n = 1.3
we will find the thickness of soap film as given by formula that is
thickness = λ/2n
thickness = 550 × / 2(1.33)
thickness = 206.76 × m
thinnest soap film is 206.76 nm