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# Tag Archives: number

## 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?

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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## Frequency of sound and loudness

What is meant by frequency? Does the loudness of sound increase with frequency?

( Thiruveni Nainar asked this question)

As you know, sound is produced by the vibrations of the sounding body. Frequency of the sound produced by the vibrations of a body is same as the frequency with which the body vibrates, i.e; the no. of vibrations completed by the body in one second.

Frequency of sound is defined as the number of vibrations completed by the sounding body per second or the number of waves crossing any point in the medium per second.

Loudness is not directly related to frequency; loudness of sound depends on the amplitude (The maximum displacement of the particles of the medium or that of the sounding body from mean position) of vibration

## Confusion with the definition of unit of time and distance.

Ram Kishore Bajpai asked: (The question is posted as such without rectifying errors.)

“Why is the time defined by distance traveled by light in vacuum 1/299,452,758?
Why does the people use a easier number such as 1/300,000,000? Why didn’t 1 second?”

It seems that you are confused a little.

The distance traveled by light in vacuum in 1/299,452,758 of a second is defined as one metre. This is because light travels 299,452,758 m in one second in vacuum.

The value 299,452,758 m/s is the speed of light calculated by various experiments and universally accepted standard.

But ordinary situations do not demand this much level of accuracy. If you correct the value 299,452,758 m/s to 1 decimal accuracy, you will get 3.0 x 108 m/s  (3,00,000 m/s) and is used in ordinary calculations requiring one or two decimal places accuracy.

## Questions from Properties of gases

we know that temperature has a properties to make some thing bigger in volume.we say that gas has no particular volume or shape.where we place a gas it takes the shape of that container.my question is- a gas of mass ‘m’ has a particular number of atoms or molecules.if the gas is not getting any temperature then how it is occupying all the volume of a bigger container.i mean how the inner space of two atoms or two molecules of that particular gas is increasing when i am transferring it to a bigger container.(say,every condition is constant.nothing is changed.)please answer me.

“can you give me some name of sites where i can get explanations on hydrostatics or the topics of physics.i am now in class 11.”

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