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Wave particle duality
Let n and m denote the number of photons emitted by a red and blue bulb respectively of equal power in a given time.Is n=m?
Answer:
No
The energy of a photon is hν
where ν is the frequency.
Power = energy/time
==> nhν1 = mhν2
==> nν1 = mν2
clearly n not equal to m
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Power Factor
Divya asked:
“A COIL HAS A POWER FACTOR OF 0.707 AT 60Hz, THEN ITS POWER FACTOR AT 180Hz WILL BE- ……….?
Ans:
(to be posted soon)
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A Problem from power
Gayathri Shinde Asks:
“Please answer this question with explanation:
The power output of a machine that lifts a 600 kg
weight through a height of 20m in 1min is:
@)1.96kW b)0.98kWc)12kW d)3.92kW”
Answer:
Use the formula power = work /time
[youtube=http://www.youtube.com/watch?v=BVxEEn3w688&rel=0&w=480&h=390]
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Power factor in AC circuits
Dany Asked:
“what is meant by power factor?”
Ans:
In AC circuits, Power factor is defined as the ratio of true power to apparent power.
If φ is the phase difference between E and I, then
True Power = EvIv cos φ and the Apparent Power is EvIv
Therefore,
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