Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

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

When a ray of light enters a medium of refractive index $\mu $ from air. It is observed that the angle of refraction is half the angle of incidence. The angle of incidence is :

  1. $2 cos^{-1}(\frac{\mu }{2})$

  2. $ cos^{-1}(\frac{\mu }{2})$

  3. $2 cos^{-1}(\mu )$

  4. $2 sin^{-1}(\frac{\mu }{2})$
Reveal answer Fill a bubble to check yourself
C 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

Refractive index of diamond with respect to glass is $1.6$ and absolute refractive index of glass is $1.5$. Find out the absolute refractive index of diamond.

  1. $1.06$

  2. $0.93$

  3. $2.4$

  4. $0.75$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Given,

Refractive index of diamond with respect to glass, ${ _{ g }{ n } _{ d } } = 1.6$,

Absolute refractive index of glass, $n _{g} = 1.5$

Refractive index of diamond with respect to glass $= \dfrac {\text {Absolute refractive index of diamond}}{\text {Absolute refractive index of glass}}$

Therefore, absolute refractive index of diamond $=$ Refractive index of diamond with respect to glass $\times$ Absolute refractive index of glass $= 1.6 \times 1.5 = 2.4$
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 is $\dfrac{4}{3}$ and of glass is $\dfrac{3}{2}$. What will be the refractive index of glass with respect to water?

  1. $9.1$

  2. $2.623$

  3. $1.125$

  4. $1$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
refractive index of water =${ _{ a }{ \mu  } _{ w }= }\dfrac { 4 }{ 2 } $
refractive index of glass = ${ _{ a }{ \mu  } _{ g }= }\dfrac { 3 }{ 2 } $

then refractive index of glass w.r.t. water is
$ _{ w }{ \mu  } _{ g }= _{ a }{ \mu  } _{ g }\times \dfrac { 1 }{ _{ a }{ \mu  } _{ w } } $
${ _{ w }{ \mu  } _{ g }= _{ a }{ \mu  } _{ g }\times \dfrac { 1 }{ _{ a }{ \mu  } _{ w } } =\dfrac { 3 }{ 2 } \times \dfrac { 3 }{ 4 } =\dfrac { 9 }{ 8 } =1.125 }$

Option C 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

In its simplest interpretation the principle of reversibility is a corollary of __________ of the refraction  of light.

  1. Snell's law

  2. Law of refraction

  3. Law of reflection

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Principle of reversibility is a corollary of snells law-

Like with reflection, refraction also involves the angles that the incident ray and the refracted ray make with the normal to the surface at the point of refraction. Unlike reflection, refraction also depends on the media through which the light rays are traveling. This dependence is made explicit in Snell's Law via refractive indices, numbers which are constant for given media1.

Snell's Law is given in the following diagram.

Basic illustration of Snell's Law.

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

Principle of reversibility holds true for

  1. Reflection

  2. Refraction

  3. Reflection and Refraction

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Path of ray of light is reversible or light traces back it's path while traveling in reverse direction or a ray of light can pass in either direction along the same path.
So
Principle of reversibility holds true for both reflection and refraction.

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 _____________ states that light will follow exactly the same path if its direction of travel is reversed. Fill the appropriate answer.

  1. Newton's law of motion

  2. Laws of reflection

  3. Laws of refraction

  4. Principle of reversibility
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The principle of reversibility of light :-

Path of ray of light is reversible or light traces back it's path while travelling in reverse direction or a ray of light can pass in either direction along the same path

Note the directions of the arrow.

The beam of light travels back on the same path as it was traveling before the refraction and after the refraction after being encountered by the obstacle in the water.

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

Principle of reversibility can applied to 

  1. Lens system

  2. Mirror system

  3. Lens and mirror system

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Principle of reversibility can applied to both lens and mirror system,
Because the principle is followed by both-Path of ray of light is reversible or light traces back it's path while traveling in reverse direction or a ray of light can pass in either direction along the same path

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 gias with respect to air is $3/2$ and that of water with respect to air is $4/3$. What is the refractive index of glass with respect to water?

  1. $9 : 8$

  2. $1 : 2$

  3. $2 : 1$

  4. $8 : 9$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Given, 


Refractive index of glass=$\dfrac{3}{2}$


Refractive index of water=$\dfrac{4}{3}$

Refractive Index of glass with respect to water= $\dfrac{3/2}{4/3}$
                         =$\dfrac{9}{8}$

Multiple choice physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

An electron having a charge e moves with a velocity v in X-direction. A magnetic field acts on it in Y-direction. The force on the electron acts in

  1. positive direction of Y-axis

  2. negative direction of Y-axis

  3. positive direction of Z-axis

  4. negative direction of Z-axis
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
As electron moving in positive x-direction, so the current  is moving in negative x-direction ( the direction of your middle finger) and the magnetic field acts on positive Y-direction ( the direction of your index finger) then thumb will be in negative Z-direction which is the direction of force. 
Multiple choice physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

A positively charged particle falls vertically downwards. The horizontal component of earths magnetic field will deflect it towards

  1. West

  2. East

  3. South

  4. North
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Using Fleming's left-hand rule, the force on a positive charge is F = q(v x B). With velocity downwards and the horizontal magnetic field component pointing North, the cross product results in a force directed towards the East.