Tag: physics

Questions Related to physics

Kirchhoff's first law ie, $\displaystyle \Sigma i=0$ at a junction is based on the law of conservation of

physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

  1. Charge

  2. Energy

  3. Momentum

  4. Angular momentum

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Correct Option: A
Explanation:

Kirchhoff's first law is based on the law of conservation of charge.

The Kirchhoff's first law $(\displaystyle\sum i=0)$ and second law $\left(\displaystyle \sum iR=\displaystyle\sum E\right)$, where the symbols have their usual meanings, are respectively based on

physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

  1. Conservation of charge, conservation of energy

  2. Conservation of charge, conservation of momentum

  3. Conservation of energy, conservation of charge

  4. Conservation of momentum, conservation of charge

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Correct Option: A
Explanation:
$\sum i=0$  (Conservation of charge).
Charge can neither be created or destroyed.
$iR=\sum E$ (Conservation of energy).
Total potential around a loop$=0$ or
Drop in Potential energy=Energy dissipated.

"A good absorber of a given wavelength of radiation is also a good emitter of that wavelength." This is a statement of:

physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

  1. Stefan-Boltzmann's law

  2. Wien's Law

  3. Kirchoff's Law

  4. The First Law of Thermodynamics

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Correct Option: C

If reflection takes place from optically denser medium, the change in phase is

conditions for a light ray to pass undeviated refraction of light at plane surfaces physics

  1. zero

  2. $\pi$

  3. $\pi / 2$

  4. $\pi / 3$

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Correct Option: B

A 5 cm thick glass slab is silvered at one of the surface to form a plane mirror. A point object is placed at a distance of $20cm $ from the unsilvered face. The image distance from the unsilvered face will be [R.I. of glass =1.5]

conditions for a light ray to pass undeviated refraction of light at plane surfaces physics

  1. 26.67cm

  2. $\frac {70}{3}$

  3. 20cm

  4. 25cm

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Correct Option: A

Light starting from a medium of refractive
index $  \mu  $ undergoes refraction into a medium of index $  \mu  $. If I and r stand for angle of incidence are refraction respectively :

conditions for a light ray to pass undeviated refraction of light at plane surfaces physics

  1. $

    \frac{\sin i}{\sin r}=\frac{\mu}{\mu^{\prime}}

    $

  2. $

    \frac{\sin i}{\sin r}=\frac{\mu^{\prime}}{\mu}

    $

  3. $

    \frac{\cos i}{\cos r}=\frac{\mu^{\prime}}{\mu}

    $

  4. $

    \frac{\sin i}{\sin r}=1 / \mu \mu^{\prime}

    $

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Correct Option: A

A small object is enclosed in a sphere of solid glass  $8 cm$  in radius. It is situated  $2 cm$  from centre and is viewed from the side to which it is nearest. Where will it appear to be it  $\mu$  of glass  $= 1.5$ ?

conditions for a light ray to pass undeviated refraction of light at plane surfaces physics

  1. $6 cm$

  2. $4 cm$

  3. $5\dfrac { 1 }{ 3 } { cm }\quad $

  4. $3\dfrac { 2 }{ 3 } { cm }$

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Correct Option: A

When a light ray is refracted from one medium into another the wavelength change from $4500{ A }^{ 0 }$ to $3000{ A }^{ 0 }$ the critial angle for a ray from second medium to first medium is 

conditions for a light ray to pass undeviated refraction of light at plane surfaces physics

  1. ${ sin }^{ -1 }\left( \dfrac { 2 }{ 3 } \right) $

  2. ${ cos }^{ -1 }\left( \dfrac { 2 }{ 3 } \right) $

  3. ${ tan }^{ -1 }\left( \dfrac { 3 }{ 2 } \right) $

  4. ${ tan }^{ -1 }\left( \dfrac { 2 }{ \sqrt { 5 } } \right) $

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Correct Option: A

Which of the following statements is false?

conditions for a light ray to pass undeviated refraction of light at plane surfaces physics

  1. A plane mirror produce a magnification of +1

  2. Focal length of a plane mirror is infinite

  3. For man of height h, to see his own complete image , a mirror of height at least equal to  h is required

  4. For a ray of light, incidenting normally on a plane mirror, the angle of reflection is $ 180^0 $

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Correct Option: C

A wave has velocity $u$ in medium $P$ and velocity $2u$ in medium $Q$. If the wave is incident in medium $P$ at an angle of $30^\circ$ then the angle of refraction will be

conditions for a light ray to pass undeviated refraction of light at plane surfaces physics

  1. $30^\circ$

  2. $45^\circ$

  3. $60^\circ$

  4. $90^\circ$

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Correct Option: D