Tag: physics

Questions Related to physics

C.V Raman's major contribution was on

physics effects of light scattering of light and its applications some natural phenomena of light natural phenomena explained by scattering

  1. Inelastic scattering of light by molecules

  2. Quantum statistics

  3. Theory of super conductivity

  4. Expanding universe

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Correct Option: A
Explanation:

Answer is A

It is also possible for the incident photons to interact with the molecules in such a way that energy is either gained or lost so that the scattered photons are shifted in frequency. Such inelastic scattering is called Raman Scattering.

Assertion: The setting sun appears to be red.
Reason: Scattering of light is directly proportional to the wavelength.

physics effects of light scattering of light and its applications some natural phenomena of light natural phenomena explained by scattering

  1.  both assertion and reason are true but the reason is the correct explanation of assertion

  2.  both assertion and reason are true but the reason is not the correct explanation of assertion

  3. assertion is true but reason is false

  4.  both the assertion and reason are false

  5. reason is true but assertion is false

Show answer
Correct Option: C
Explanation:

Setting sun appears to be red because red light which has greatest wavelength is least scattered and reaches our eyes the most. Other wavelength are scattered to the longest extent. So, reason given is wrong.

Assertion: By roughening the surface of a glass sheet its transparency can be reduced.
Reason: Glass sheet with rough surface absorbs more light.

physics effects of light scattering of light and its applications some natural phenomena of light natural phenomena explained by scattering

  1. Both assertion and reason are true and reason is the correct explanation of assertion

  2. Both assertion and reason are true but the reason is not the correct explanation of assertion

  3. Assertion is true but reason is false.

  4. Both the assertion and reason are false

  5. Reason is true but assertion is false

Show answer
Correct Option: C
Explanation:
When a glass surface is made rough, light falling on it gets scattered. Due to this, transparency of glass is reduced.
Hence, assertion is correct and reason is wrong.

Larger particles scatter light at the ____ end of the spectrum the least.

physics effects of light scattering of light and its applications some natural phenomena of light natural phenomena explained by scattering

  1. Blue

  2. Green

  3. Violet

  4. Red

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Correct Option: D
Explanation:

Larger particles scatter light at the red end of the spectrum the least as the amount of scattering decreases with increase in wavelength..

In a beaker containing colloidal solution of sodium thiosulphate and a drop of con. sulphuric acid, light observed from side of beaker is:

physics effects of light scattering of light and its applications some natural phenomena of light natural phenomena explained by scattering

  1. Blue

  2. Red

  3. Green

  4. Yellow

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Correct Option: A
Explanation:

Colloidal solution of sodium thiosulphate consists of fine particles that mainly scatters blue light. Hence, it appears blue from the side of the beaker.

When is the direction of scattered light independent of the wavelength?

physics effects of light scattering of light and its applications some natural phenomena of light natural phenomena explained by scattering

  1. Medium of travel is not air.

  2. Particles involved in scattering have size smaller than the wavelength of the incident light wave.

  3. Particles involved in scattering have size larger than the wavelength of the incident light wave.

  4. Particles scattering the light wave are not neutral in charge.

Show answer
Correct Option: C
Explanation:

Particles smaller than the wavelength of light scatters the light in all directions. In visible spectrum, they scatter violet the most and red the least. However, when the particles are larger than the wavelength of light, then the scattering of all wavelengths occur to same extent.

Rising and setting sun appears to be reddish because:

physics effects of light scattering of light and its applications some natural phenomena of light natural phenomena explained by scattering

  1. The sun is colder at sunrise or at sunset

  2. Diffraction sends red rays to the earth at these times

  3. Refraction is responsible for it

  4. Scattering due to dust particles and air molecules is responsible for it

Show answer
Correct Option: D
Explanation:

According to Rayleigh's law of scattering, amount of scattering $\alpha \frac {1}{\lambda^4}$.
Red having maximum wavelength straight to the observer.
Most of the scattered light goes towards the sky, so the sky appears blue.

The process of re-emission of absorbed light in all directions with different intensities by the atom or molecule is called ____________.

physics effects of light scattering of light and its applications some natural phenomena of light natural phenomena explained by scattering

  1. Scattering of light

  2. Dispersion of light

  3. Reflection of light

  4. Refraction of light

Show answer
Correct Option: A
Explanation:

$Scattering$ is the process of absorbed light in all possible directions with different intensities and frequency by an atom or a molecule.


Answer-(A)

If slope of tangent of curve $y=\dfrac{x}{b-x}$ at $(1,1)$ be $2$ then $b=$

physics parametric equations proving properties of curves derivatives - introduction and interpretation introduction to calculus - differentiation

  1. $1$

  2. $2$

  3. $0$

  4. $-1$

  5. $-2$

Show answer
Correct Option: B
Explanation:

Given,

$y=\dfrac{x}{b-x}$
Now,
$\dfrac{dy}{dx}=\dfrac{(b-x)1+x.(-1)}{(b-x)^2}$
or, $\dfrac{dy}{dx}=\dfrac{b}{(b-x)^2}$.
Now,
$\left.\dfrac{dy}{dx}\right| _{(1,1)}=\dfrac{b}{(b-1)^2}$.
According to the problem,
$\dfrac{b}{(b-1)^2}=2$
or, $b=2(b^2-2b+1)$
or, $2b^2-5b+2=0$
or, $(2b-1)(b-2)=0$
or, $b=\dfrac{1}{2}, 2$.

The general solution of the differential equation $\sin{2x}\left( \cfrac { dy }{ dx } -\sqrt { \tan { x }  }  \right) -y=0$ is $y\phi(x)=x+c$ then ${ \Phi  }^{ 1 }\left( \cfrac { \pi  }{ 4 }  \right) $ is _____

physics parametric equations proving properties of curves derivatives - introduction and interpretation introduction to calculus - differentiation

  1. $1$

  2. $-1$

  3. $\cfrac{1}{\sqrt{3}}$

  4. $\sqrt{-3}$

Show answer
Correct Option: B
Explanation:

$\displaystyle \frac{dy}{dx}-\text{cosec}2x y=\sqrt{\tan x};I.F=e^{\displaystyle \int-\text{cosec}2xdx}$

$=\sqrt{\text{cosec }2x+\text{cot} 2x} \implies y\sqrt{\text{cosec}2x+\text{cot}2x}=x+c\implies \phi'\bigg(\frac{\pi}{4}\bigg)=-1$