Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice physics option a: relativity maxwell's equations the nature of light introduction to electromagnetic waves

Which of the following conclusion can be drawn from the result $\oint \bar{B}\cdot d\bar{A}=0$

  1. Magnetic field is zero everywhere

  2. Magnetic monopole cannot exist

  3. Magnetic lines of force do not intersect each other

  4. A current produces magnetic field
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Flux of certain closed surface is zero and so it tells that net magnetic charge is equal to zero. This is possible when there are two equal and opposite poles.

Multiple choice physics option a: relativity maxwell's equations the nature of light introduction to electromagnetic waves

Which of the following effects could not be explained by Maxwell's electromagnetic wave theory?

  1. Photoelectric effect

  2. Compton effect

  3. Raman effect

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

  1. Photoelectric effect was discovered by heinrich Rudoy Hertz.
  2. Compton effect was discovered by Aethur Holl Compton.
  3. Raman effect was discovered by Sir Chandrasekhar Venbata Ram. 
      So, none of these effect was discovered by Maxwell.

Multiple choice physics option a: relativity maxwell's equations the nature of light introduction to electromagnetic waves

A parallel plate capacitor having plate area A and plate separation $d$ is connected to a battery of emf $\varepsilon$ and internal resistance $R$ at $t=0$. Consider a plane surface of area $\dfrac{A}{2}$, parallel to the plates and situated symmetrically between them. Find the displacement current through this surface as a function of time?

  1. $\dfrac {-\varepsilon}{2R} \ \ \ e^{\dfrac{-td}{\varepsilon AR}}$

  2. $\dfrac {2\varepsilon}{R} \ \ \ e^{\dfrac{-td}{\varepsilon AR}}$

  3. $\dfrac {5\varepsilon}{2R} \ \ \ e^{\dfrac{-td}{4 \varepsilon AR}}$

  4. $\dfrac {\varepsilon}{2R} \ \ \ e^{\dfrac{-td}{4\pi \varepsilon AR}}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The displacement current in a charging capacitor is equal to the conduction current in the circuit. The current in an RC circuit is I(t) = (epsilon/R) * e^(-t/RC). Since the surface area A/2 is parallel to the plates, it intercepts half the electric flux, leading to a factor of 1/2.

Multiple choice physics option a: relativity maxwell's equations the nature of light introduction to electromagnetic waves

According to Maxwell's hypothesis, changing of electric filed give rise to

  1. magnetic field

  2. pressure gradient

  3. charge

  4. voltage
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to Maxwell's hypothesis, changing of electric field gives rise to Magnetic field.

We know that $F=qE,$, where $F$ is force and $E$ is electric field.
We can relate magnetic field and force by $F=qvB$, where $v$ is velocity and $B$ is the magnetic field.
Therefore we can obtain magnetic field by changing electric field.
Therefore option $A$ is correct.

Multiple choice physics option a: relativity maxwell's equations the nature of light introduction to electromagnetic waves

Unpolarized light falls first on polarizer $\left( P \right) $ and then on analyzer $\left( A \right) $. If the intensity of the transmitted light from the analyser is $\dfrac { 1 }{ 8 }$th of the incident unpolarized light. What will be the angle between optic axes of $P$ and $A$?

  1. ${ 45 }^{ o }$

  2. ${ 30 }^{ o }$

  3. Zero

  4. ${ 60 }^{ o }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Given,
$I=\dfrac { { I } _{ 0 } }{ 2 } $              ....(i)
${ I }^{ ' }=I\cos ^{ 2 }{ \theta  } $                 $\left( \because { I }^{ ' }=\dfrac { { I } _{ 0 } }{ 8 }  \right) $
$\therefore \dfrac { { I } _{ 0 } }{ 8 } =\dfrac { { I } _{ 0 } }{ 2 } \cos ^{ 2 }{ \theta  } $
From the equation (i), we have
$\dfrac { 1 }{ 4 } =\cos ^{ 2 }{ \theta  } \Rightarrow \cos { \theta  } ={ 1 }/{ 2 }$
$\Rightarrow \cos { \theta  } =\cos { { 60 }^{ o } } $
$\Rightarrow \theta ={ 60 }^{ o }$

Multiple choice physics option a: relativity maxwell's equations the nature of light introduction to electromagnetic waves

A plane electromagnetic wave with an intensity of $200 W/m^2$ is incident normal to a flat plate of radius 30 cm. If the plate absorbs $60%$ and reflect $40%$ of the incident radiation, what is the momentum transferred to it in 5 min?

  1. $1.7 \times 10^{-3} kg ms^{-1}$

  2. $2.7 \times 10^{-4} kg ms^{-1}$

  3. $3.7 \times 10^{-4} kg ms^{-1}$

  4. $3.7 \times 10^{-3} kg ms^{-1}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice physics light : reflection and refraction from plane surface principle of reversibility of path of light image formation by plane mirror refractive index

If refraction index of glass with respect to air is $ _{a}{u} _{g} = \dfrac{3}{2}$, the refraction index of air with respect to glass will be $ _{g}{u} _{a} =$

  1. ${3}/{2}$

  2. ${2}/{3}$

  3. ${1}/{3}$

  4. ${1}/{2}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
refractive index of glass w.r.t air =${ _{ a }{ \mu  } _{ g }= }\dfrac { 3 }{ 2 } $
then,
refractive index of air w.r.t glass  =$ _{ g }{ \mu  } _{ a }=\dfrac { 1 }{ _{ a }{ \mu  } _{ g } } $

$ _{ g }{ \mu  } _{ a }=\dfrac { 1 }{ _{ a }{ \mu  } _{ g } } =\dfrac { 2 }{ 3 } $
Option B is correct.
Multiple choice physics light : reflection and refraction from plane surface principle of reversibility of path of light image formation by plane mirror refractive index

The refractive index of water with respect to air is $ _{a}{u} _{w}$ and of glass with respect to air is $ _{a}{u} _{g}$. Express the refractive index of glass with respect to water

  1. $\dfrac{ _{a}{u} _{g}}{ _{a}{u} _{w}}$

  2. $\dfrac{ _{g}{u} _{a}}{ _{a}{u} _{w}}$

  3. $\dfrac{ _{a}{u} _{w}}{ _{a}{u} _{g}}$

  4. $\dfrac{ _{a}{u} _{a}}{ _{g}{u} _{g}}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Refractive index of water w.r.t air
$ _{a}\mu _{w}=\dfrac{\mu _{w}}{\mu _{a}}$
Refractive index of glass w.r.t air
$ _{a}\mu _{g}=\dfrac{\mu _{g}}{\mu _{a}}$
Hence refractive index of glass w.r.t water
$ _{w}\mu _{g}=\dfrac{\mu _{g}}{\mu _{w}}   =\dfrac{ _{a}\mu _{g}}{ _{a}\mu _{w}}$

Multiple choice physics light : reflection and refraction from plane surface principle of reversibility of path of light image formation by plane mirror refractive index

At ray of light is incident in medium 1 at an angle of $37^{o}$ and gets refracted in medium 2 at an angle of $53^{o}$. What will be angle of refraction if light is incident in medium 2 at an angle of $53^{o}$.

  1. $37^{o}$

  2. $53^{o}$

  3. $36^{o}$

  4. $45^{o}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Principle of reversibility states that when final path of a ray of light after any number of reflections and refractions is reversed, the ray retraces its entire path or in simple words, light follows exactly the same path if its path of travel is reversed.

Thus angle of refraction of light in medium $1$ will be $37^o$.