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galina1969 [7]
3 years ago
9

A lamp is 10% efficient.How much electrical energy must be supplied to the lamp each second if it produces 20 J of light energy

per second?
Physics
1 answer:
k0ka [10]3 years ago
6 0

If it produces 20J of light energy in a second, then that 20J is the 10% of the supply that becomes useful output.

20 J/s = 10% of Supply

20 J/s = (0.1) x (Supply)

Divide each side by 0.1:

Supply = (20 J/s) / (0.1)

<em>Supply = 200 J/s  </em>(200 watts)

========================

Here's something to think about:  What could you do to make the lamp more efficient ?  Answer:  Use it for a heater !

If you use it for a heater, then the HEAT is the 'useful' part, and the light is the part that you really don't care about.  Suddenly ... bada-boom ... the lamp is 90% efficient !

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Why is a protective apron or lab coat important to use when working with acids?
Kipish [7]

Answer:

Acids break down fabrics and can cause burns if the acids are strong.

Explanation:

A protective apron or lab coat is important when working with acids because acids break down fabrics and can cause burns if the acids are strong.

  • An acid is a substance that interacts with water to produce excess hydroxonium ions in an aqueous solution.
  • A strong acid ionizes completely in solution.
  • When they come in contact with a fabric, they break them down violently.
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4 0
3 years ago
Read 2 more answers
20. The speed of Light is 3.0 x 108 m/s. Blue Light has a frequency of 6.11 x 1014 Hz. What is its wavelength?
Sladkaya [172]

Answer:

4.91 x 10⁻⁷ m

Explanation:

the applicable formula is

v = fλ

where

v = velocity (i.e speed) = given as 3.0 x 10⁸ m/s

f = frequency = given asw 6.11 x 10¹⁴

λ = wavelength

if we rearrange the equation and substitute the values given above,

v = fλ

λ = v/f  

= 3.0 x 10⁸ / 6.11 x 10¹⁴

= 4.91 x 10⁻⁷ m

5 0
3 years ago
Except for the nodes on a standing wave, what is the frequency f of the points executing simple harmonic motion?
Katen [24]

Take into account that in a standing wave, the frequency f of the points executing simple harmonic motion, is simply a multiple of the fundamental harmonic fo, that is:

f = n·fo

where n is an integer and fo is the first harmonic or fundamental.

fo is given by the length L of a string, in the following way:

fo = v/λ = v/(L/2) = 2v/L

becasue in the fundamental harmonic, the length of th string coincides with one hal of the wavelength of the wave.

6 0
1 year ago
10. A boat traveling at 9.5 m/s reduces its acceleration at a rate of 2.5 m/s2. What is the final speed of the boat
Fiesta28 [93]

Answer:

6.75m/s

Explanation:

using the second equation of motion, the time is calculated.

and with the formula a= (v - u)/t

where a is acceleration but in this case it's deceleration (and should be negated as you solve it ) .

v is final velocity

u is initial velocity

t is time taken

7 0
2 years ago
Which wave property changes when two waves interfere in the same medium?
LuckyWell [14K]
<span>When two waves of same frequency travel in a medium simultaneously in the same direction then, due to their superposition, the resultant intensity at any point of the medium is different from the sum of intensities of the two waves. At certain points the intensity of the resultant wave has a large value while at some points it has a very small or zero. This is called wave interference.</span>
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