Physics, 29.08.2019 23:30 edjiejwi

An individual white led (light-emitting diode) has anefficiency of 20% and uses 1.0 w of electric power.
a) how many leds must be combined into one light sourceto give a total of 1.6 w of visible-light output (comparableto the light output of a 40 w incandescent bulb)?
b) what total power is necessary to run this led lightsource?

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Answer from: kimlyn58p0wyn0

a) There must be 8 LED's combined into one ligth source to give a total of 1.6W of visible-light output.

b) The total power necessary to run this LED lightsource is 8.0W

Explanation:

a) According to this problem, each white LED will have an efficiency of 20%. This means that each LED will use only 20% of all the inputed power and turn it into visible light. The rest of the power will turn into heat loss.

So taking this into account, let's take the total amount of power each LED will consume and let's multiply it by it's efficiency.

$P_{converted}=P_{consumed}*N$

Where N is the efficiency, so we get:

$P_{converted}=1.0W*0.20=0.20W$

So from this equation we know now that each LED will turn 0.20W of the energy consumed into light.

Once we have this data we can use conversions to find the number of LED's needed to give a total of 1.6W of visible-light output. So we get:

$1.6W*\frac{1LED}{0.2W}=8LED's$

So the we need 8 LED's to get a total of 1.6W of visible-light output.

b) Since we need 8 LED'S on our lightsource and we know that each LED will consume a total of 1.0W, then all we need to do is multiply the number of LED's by the number of Watts consumed to get the total of Watts consumed by the LED's.

$P_{total}=8LED's*\frac{1.0W}{1LED}=8.0W$

So the total power necessary to run this LED lightsource is 8.0W

Answer from: Quest

An atom (ours, not carroll's) consists of a positively charged nucleus, surrounded by one or more negatively charged particles called electrons. the positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral. most of an atom's mass is in its nucleus; the mass of an electron is only 1/1836 the mass of the lightest nucleus, that of hydrogen. although the nucleus is heavy, it is quite small compared with the overall size of an atom. the radius of a typical atom is around 0.1 to 0.25 nanometres (nm), whereas the radius of a nucleus is about 10-6 nm. * if an atom were enlarged to the size of the earth, its nucleus would be only 200 feet in diameter and could easily rest inside a small football stadium.read more on -

Answer from: Quest

50 meters per 5 seconds

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