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)
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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 !
Answer:
Explanation:
Given
initially mass is stretched to 
Let k be the spring Constant of spring
Therefore Total Mechanical Energy is 
Position at which kinetic Energy is equal to Elastic Potential Energy


it is given

thus 



Answer:
10.0 zero, by Gauss' Law the symmetrical distribution will produce no internal electric fields
21.5 E = k Q / R^2 behaves as if all charge were at center
E = 9 E9 * 29.5 E-6 / .215^2 = 5.74E6 N/C
<span>This is not a good answer, because some one t o forgot to tell us the important temperature, and the given atmospheric pressure "at sea level" makes really no sense. In SI units with dry air at 20°C (68°F), the speed of sound c is 343 meters per second (m/s).</span>
Answer:
For metric-system conversions, follow this method: Sound travels at about 340 m/s, so multiply the number of seconds you counted by 340, and you'll know how many meters away lightning struck. A three-second count, then, would place the lightning strike about 1,020 m away, or roughly 1 km.
Explanation:
hope it hep and if it doesnt sorry