Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice physics wave optics wave behaviour huygens wave theory and wavefront wave propagation (huygens' construction)

Wave front means:

  1. all particles in it have same phase

  2. few particles are in same phase, rest are in opposite phase

  3. all particles have opposite phase of vibrations

  4. all particles have random vibrations
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

All particles in it have same phase.

It is the imaginary surface representing corresponding points pf a wave that vibrate in unison. When identical waves having a common origin travel through a homogeneous medium , the corresponding crests and troughs at any instant phase.

Multiple choice physics wave optics wave behaviour huygens wave theory and wavefront wave propagation (huygens' construction)

A wavefront is an imaginary surface where :

  1. phase is same for all points

  2. phase changes at constant rate at all points along the surface

  3. constant phase difference continuously changes between the points

  4. phase changes all over the surface
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A wave front is the locus of points having the same phase.
Hence option A is correct.

Multiple choice physics wave optics wave behaviour huygens wave theory and wavefront wave propagation (huygens' construction)

The wavefront of a light beam is given by the equation $x + 2 y + 3 z = c$ , (where c is arbitrary constant) then what is the angle made by the direction of light with the y-axis?

  1. $\cos ^ { - 2 } \frac { 2 } { \sqrt { 14 } }$
  2. $\cos ^ { - 1 } \frac { 2 } { \sqrt { 14 } }$
  3. $\cos ^ { - 3 } \frac { 2 } { \sqrt { 14 } }$
  4. $\cos ^ { - 4 } \frac { 2 } { \sqrt { 14 } }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The wave front equations must be of form $ax+by+cz=1$ where ${a^2} + {b^2} + {c^2} = 1$ 

$($ $a,b,c$ are cosines of angles made with $x,yx,z$ axes respectively $)$
applying this to the given equation$:$
${1^2} + {2^2} + {3^2} = {c^2}$
${c^2} = 14$
$c = \sqrt {14} $
${\cos ^{ - 1}}\dfrac{2}{{\sqrt {14} }}$
angle made with $y-$ axis is ${\cos ^{ - 1}}\dfrac{2}{{\sqrt {14} }}$
Hence,
option $(B)$ is correct answer. 

Multiple choice physics wave optics wave behaviour huygens wave theory and wavefront wave propagation (huygens' construction)

The wavefront is a surface in which

  1. all points are in the same phase

  2. there is a pair of points in opposite phase
  3. there is a pair of points with phase difference $(\dfrac{\pi}{2})$

  4. there is no relation between the phases
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A wavefront is the locus of points characterized by propagation of position of the same phase: a propagation of a line in 1D, a curve in 2D or a surface for a wave in 3D.

Multiple choice uniform magnetic field lines of earth magnetism physics

In null method of comparison of magnetic moments, the net magnetic field at the centre of the DMM, when null deflection is obtained is

  1. $0$
  2. $B _{H}$
  3. between $0$ and $B _{H}$
  4. above $B _{H}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In null method , two magnets are kept on either side of the arms so that the net deflection is zero . So the magnetic field due to the bar magnets gets cancelled and only earth's horizontal magnetic field is left

Multiple choice uniform magnetic field lines of earth magnetism physics

In both $\tan A$ and $\tan B$ positions in a Deflection Magnetometer,  the bar magnet is always placed

  1. parallel to the magnetic needle of the deflection magnetometer

  2. parallel to the aluminum pointer of the deflection magnetometer

  3. perpendicular to the aluminum pointer

  4. parallel to the arm having the wooden scale
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In $\tan A$ position the bar magnet is placed horizontally, parallel to the arm of the deflection magnetometer and parallel to the magnetic needle of the deflection magnetometer. 

In $\tan B$ position the bar magnet is placed horizontally, perpendicular to the arm of the deflection magnetometer and parallel to the magnetic needle of the deflection magnetometer. 

Multiple choice uniform magnetic field lines of earth magnetism physics

The absolute value of earths magnetic horizontal intensity is determined with the help of

  1. DMM only

  2. VMM only

  3. DMM & VMM

  4. Plane mirror
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The absolute value of earths magnetic horizontal intensity is determined with the help of DMM and VMM.