Question

I am completing a study guide for the next section of class because I am trying to get ahead. Any suggestions?
A wave whose displacement velocity is either in the same direction or opposite direction as the wave velocity describes which type of a wave? a. Transverse wave b. Mechanical wave c. Longitudinal wave d. Electromagnetic wave Which of the following are always one wavelength apart and are drawn as parallel lines? Plane waves b. Wave fronts c. Wave phase If a wave in a diamond having a wavelength of A travels from the diamond (n 2.50) into water (n-1.50), what is its new wavelength? 3/22 b. 2/3A c. 5/2A d. 2/5λ e. 3/5A f. 5/3A Which of these phenomenons is not accounted for by the principle of supper position? a. Standing waves on a string b. Thin film interference c. Doppler effect d. Beat frequency Which of the following will always result in a higher perceived frequency? a. Both the source and observer moving away from each other b. Both the source and observer moving towards each other c. The Source moving towards and the observer moving away d. The Source moving away and the observer moving towards.

Answer 1

(1) Answer : c. Longitudinal wave

For transverse waves the displacement of the medium is perpendicular to the direction of propagation of the wave.

electromagnetic waves are transverse wave.

Mechanical wave are material waves . They can have transverse like propagation and other types of too.

Only in the longitudinal waves the particles displacement velocity is in the same direction as the wave velocity.

Example : Sound.

(2) Answer : b. Wave fronts

Wave fronts are always drawn as parallel lines and distance between two wave fronts are always equals to the wavelength of the wave.

Phase is the position of a point in time.

Plane waves :  A wave whose surfaces of constant phase are infinite parallel planes normal to the direction of propagation. That would then correspond to a lossless energy propagation.

(3) Answer : f. $\dpi{100} 5 \lambda/ 3$

The relation of wave speed ($\dpi{100} v$) with frequency($\dpi{100} f$) and wavelength ($\dpi{100} \lambda$) is

  $\dpi{100} v = f \lambda$

And the refractive index of any medium in which the wave speed is $\dpi{100} v$ , is given by

  $\dpi{100} n = \frac{C}{v}$ (C is speed of light)

So, $\dpi{100} n = \frac{C}{f \lambda}$

When wave propagates from one medium to another the frequency of light does not change.

When wave travels through the diamond

  $\dpi{100} n_{diamond} = \frac{C}{f \lambda}$

or,   $\dpi{100} \frac{C}{f \lambda} = 2.50$

When wave goes into the water, let the new wavelength is $\dpi{100} \lambda _{0}$ then

$\dpi{100} \frac{C}{f \lambda _{0}} = 1.50$

Comparing these two equations , we can write

$\dpi{100} \lambda _{0} = \frac{2.50}{1.50} \, \lambda = \frac{5 \lambda }{3}$

(4) Answer : c. Doppler effect

Doppler effect is the change in the frequency of sound, light, or other waves as the source and observer move towards (or away from) each other.

And all other phenomena like Standing wave on string, Thin film interference and Beat frequency can be described on the basis of principle of superposition.

(5) Answer : b. Both source and observer moving towards each other

The Doppler effect is given by

  $\dpi{100} f = f_{0} \, \left ( \frac{v \pm v_{O}}{v \pm v_{s}} \right )$

Where, $\dpi{100} v$  is the velocity of waves in the medium;

  $\dpi{100} v_{O}$ is the velocity of the receiver relative to the medium; positive if the receiver is moving towards the source (and negative in the other direction);

$\dpi{100} v_{s}$ is the velocity of the source relative to the medium; positive if the source is moving away from the receiver (and negative in the other direction).

For $\dpi{100} f$ to be maximum the most suitable condition is

$\dpi{100} f = f_{0} \, \left ( \frac{v + v_{O}}{v - v_{s}} \right )$

(6) I have marked the point on wave for x = 17 m , as you can see the displacement of particle at this position is -4 m.

Did you know asking more than one question at a time is against the policy. Still i have solved first 6 problems. If you need all the answers please upload remaining problems separately.

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