Definition of phosphorescence

1 answer:

4 0

Light emitted by substance without combustion or perceptible heat emission of radiation in a similar manner to florescence but on a longer time scale so that emission continues after excitation ceases.

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What could happen if a black whole eat earth

hram777 [196]

We would all die and theres no way of coming out of a black hole. What's in it is unknown.

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3 years ago

Hold a spoon such that the water will hit the back of the spoon. The handle of the spoon will be horizontal. Turn on the water,

antoniya [11.8K]

This is an experiment that explains the Bernoulli principle. According to this principle, at the bottom of the spoon, there will be a reduction in pressure.

<h3>Explanation of the Bernoulli principle</h3>

So the pressure at the bottom of the spoon reduces because the velocity of the water is larger and the height of the column of water is smaller at this part.

So the spoon is attracted to the water at the point of lowest pressure because objects gravitate to low-pressure points.

Learn more about the Bernoulli Principle at:

brainly.com/question/24623919

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2 years ago

Determine the length of the tungsten filament in a 100 watt lightbulb given: (i) the resistivity of tungsten is 5.6 × 10−8 Ω · m

svetoff [14.1K]

Answer:

0.34148 m

Explanation:

$\rho$ = Resistivity of tungsten = $5.6\times 10^{-8}\ \Omega m$

d = Diameter = 0.0018 inch

r = Radius = $\dfrac{r}{2}=\dfrac{0.0018}{2}=0.0009\ in$

$r=0.0009\times 0.0254=0.00002286\ m$

$\alpha$ = Temperature coefficient of tungsten = $0.0045 /^{\circ}C$

Power is given by

$P=\dfrac{V^2}{R}\\\Rightarrow R=\dfrac{V^2}{P}\\\Rightarrow R=\dfrac{120^2}{100}\\\Rightarrow R=144\ \Omega$

We have the equation

$R_2=R_1[1+\alpha(T_2-T_1)]\\\Rightarrow R_1=\dfrac{R_2}{1+\alpha(T_2-T_1)}\\\Rightarrow R_1=\dfrac{144}{1+0.0045(2550-25)}\\\Rightarrow R_1=11.64812\ \Omega$

Resistance is given by

$R=\rho\dfrac{l}{A}\\\Rightarrow l=\dfrac{RA}{\rho}\\\Rightarrow l=\dfrac{11.64812\times \pi (0.00002286)^2}{5.6\times 10^{-8}}\\\Rightarrow l=0.34148\ m$