Question

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?

Answer 1

Answer:

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 2

Electric power is the power or energy transmitted by a electric source or circuit per unit time.

• a) The total number of LEDs required is 8.

• b) Total power is necessary to run this LED light source 8 watt.

What is electric power?

Electric power is the power or energy transmitted by a electric source or circuit per unit time.

Given information-

The an efficiency of the individual white LED  is 20%.

The power use of the LED is 1.0 W of electric power.

• a) The number of LEDs combined into one light source to-

For part a we have given that,

The total of 1.6 W of visible-light output.

The light output of a 40 W incandescent bulb.

The power used by the LED is  20%. in the power of 1.0 W. Thus the power used by one LED is,

$P=1\times\dfrac{20}{100} \\P=0.2 \rm W$

As the total power consumed is 1.6 W. and the  power consumed by the one LED is 0.2 watt. Thus the total number of LED need to use 1.6 W are,

$n=\dfrac{1.6}{0.2}\\n=8$

Hence, the total number of LEDs required is 8.

• b) The total power is necessary to run this LED light source-

There is total number of LED is 8 and the power of 1 LED consumed is 1 W. Thus the  total power is necessary to run this LED light source is,

$P=8\times1\\P=8\rm W$

Hence, total power is necessary to run this LED light source 8 watt.

Hence,

• a) The total number of LEDs required is 8.
• b) Total power is necessary to run this LED light source 8 watt.

Learn more about the electric power here;

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