Tag: physics

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Questions Related to physics

Multiple choice physics world of sounds characteristics of sound wave time period, frequency and amplitude of sound sound waves are longitudinal waves

The velocity of sound in air is not affected by change in 

  1. the moisture content of the air.

  2. the temperature of air.

  3. the atmospheric pressure.

  4. the composition of air.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The speed of sound depends on temperature. The formula relating speed of sound and temperature is as follows:

$v = 331 + 0.6 \times T$, where $T$ is temperature in absolute scale and $v$ is in $m/s$.
Humidity has little effect on the speed of sound.
Air pressure has no effect at all in an ideal gas approximation. This is because pressure and density both contribute to sound velocity equally, and in an ideal gas the two effects cancel out each other, leaving only the effect of temperature.
Composition of air has also almost no effect on the speed of sound.

Multiple choice physics world of sounds characteristics of sound wave time period, frequency and amplitude of sound sound waves are longitudinal waves

Consider the following
l. Waves created on the surfaces of a water pond by a vibrating source.
ll. Wave created by an oscillating electric field in air.
lll. Sound waves travelling under water. 
Which of these can be polarized

  1. l and ll

  2. ll only

  3. ll and lll

  4. l, ll, and lll
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sound waves are longitude and can not be polarized. Answer A

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

Choose the Correct answer from alternative given.
The idea of secondary wavelets for the propagation of a wave was first given by:

  1. Newton

  2. Huygens

  3. Maxwell

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

According to the Huygens theory, all the points on a  wavefront act as source for a secondary wavefront or a wavelet which spread outward from the point and move at the speed of light.

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

The wavelength of characteristic $X \text { -ray } K _ { \alpha }$ a line emitted by hydrogen like atom is $0.32 \mathrm { A } ^{ \circ }$. The wavelength of $K _ { \beta }$ line emitted by the same element is 

  1. $0.21 { \mathrm { A } }$
  2. $0.27 \mathrm { A }$
  3. $0.33 \mathrm { A }$
  4. $0.40 \hat { \mathrm { A } }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice physics wave optics huygens wave theory and wavefront wave propagation (huygens' construction) theories on light wave behaviour

A transverse wave travelling in a denser medium is reflected from a rarer medium. Then, 

  1. an incident crest is reflected as a crest

  2. an incident crest is reflected as a trough
  3. there is a phase change of $2\pi$ rad
  4. there is a phase change of $\pi/2$ rad
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When a wave reflects from a rarer medium, there is no phase change. Therefore, the crest remains a crest and the trough remains a trough.