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spin [16.1K]
3 years ago
14

A lightbulb has an effciency of 8.2%. How much light energy (not heat energy) is generated by the bulb every second if the buld

has pwer of 21w?
Physics
1 answer:
telo118 [61]3 years ago
8 0
It really depends on what the bulb is being used for, since efficiency means how much of the output is USEFUL.
If the bulb is being used for light in a dark room, then it produces (8.2% x 21W) = 1.72 joules per second of light energy.
If the bulb is being used to keep a hamster cage or a fish tank warm, then the 8.2% is the useful part, and the light is the other (91.8% x 21W) = 19.28 joules per second.
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Farmer Wilcox wants to reduce the wind velocity near his farm. He should _____.
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Plant trees around the perimeter of his fields
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Which equation was used by Albert Einstein to explain the photoelectric effect? [E = energy, h = Planck’s constant, and v = freq
Afina-wow [57]

Answer:

E = hv

Explanation:

  • The photoelectric effect is a phenomenon when the electromagnetic waves of a particular wavelength strike on the metal plate like zinc, it ejects the free electrons.
  • The ejected electrons have the kinetic energy and this energy is responsible for the electric energy.
  • The kinetic energy of the emitted electrons is linked with the frequency of the incident rays.
  • If the rays hitting the metal plate is below the minimum required threshold value, the photoelectrons are not ejected.
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6 0
3 years ago
| A 1.0 kg stone is dropped from a bridge 100 m above a canyon. What will be the kinetic energy of the stone after it
Mnenie [13.5K]

Answer:

Option D

490 J

Explanation:

When at a height of 100 am above and released, the ball initially posses only potential energy. When it falls, some potential energy is converted to kinetic energy.

Initial potential energy= mgh where m is the mass, g is the acceleration due to gravity and h is height. Substituting 1 Kg for m, 9.81 for g and 100 m for h then

PE initial = 1*9.81*100= 981 J

At 50 m, PE will be 1*9.81*50=490.5 J

Subtracting PE at 50 m from initial PE we get the energy that has been converted to kinetic energy hence

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Approximately, 490 J

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Which of the following is not a property of displacement?
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This is something that is definitely not a displacement.

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4 years ago
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