بدون تحميل أهم 100 سؤال فى مادة فيزياء لغات - الجزء الثالث

أهم 100 سؤال فى مادة الفيزياء لغات - الجزء الثالث



what is meant by each of the following;


The distance between node and successive antinode is 2 cm.

The wavelength of the stationary wave = 4x0.02 =0.08m

The wave length of a standing wave in a stretched string = l0 cm.

Double the distance between two successive nodes or two successive antinodes = 10 cm.

The distance between two successive nodes of a stationary wave is 5 cm.

The wavelength of the stationary wave =2x0.05=0.1m


Second;multiple choice questions(M.C.Q)


The figure shows waves produced by two sources(s1,s2)


The figure indicates :

a) Sound reflection.

b) Sound refraction.

c) Sound interference.

d)Sound diffraction.


In the figure:

a)the distance AE. = the distance DE =

b)the distance AE =the distance BD =

c)the distance CB < the distance BD

d)all previous are correct


Which of the following properties change when a wave is refracted?

a)speed only

b)wavelength only

c)frequency only

d)Speed and wavelength


In the opposite diagram two different transverse pulse propagate
in opposite direction along the same rope when the
two pulse combined exactly at the midpoint x the amplitude of them
equals

a) +1 cm b) -1 cm c) 7cm


The wave length of a standing wave is ………

a)The distance between two successive nodes

b)the distance between two successive antinodes

c) twice the distance between two successive nodes


The relation between the frequency of the fundamental tone and
the frequencies of the harmonic tones in stretched string is given by
…….

a)1:2:3 b) 1:3:4 c)1:3:5



The string emits its second harmonic tone when it vibrates in the form of . . . .

a)Three segments b)four segment c)two segments

The wavelength (λ) of the third harmonic tone, which is produced from a


Stretched string of length (L), is determined from the relation. . . .



cالإجابة الصحيحة

When a string of length (L) vibrates and is divided into (n)
segment then the wave length of its tone (λ) equals.. . . . . . . . . .
. .



aالإجابة الصحيحة

The length of a stretched string (L) which emits its first overtone is related to Wavelength () by the relation



dالإجابة الصحيحة

Stationary transverse waves are set up in a stretched string as
shown The distance between the fixed points is 60cm. For one
particular frequency, the pattern shown is formed. What is the
wavelength?

a)20cm b)40cm c)60cm d)120cm


bالإجابة الصحيحة

Thired; Give reasons



Sound Diffraction can easily detect than that of light.

Because, the wavelength of sound longer than light.

We can hear a person talking behind a thick wall or in a neighboring room.

Due to diffraction of sound waves as the wave change its direction at the edges of the obstacle.


When a stretched string oscillates to produce its fundamental
frequency the length of the string becomes equal to one-half the
wavelength of the produced tone.

When the string emits its fundamental frequency, it produce one
segment including two successive nodes, the distance between them equals
one-half of the wavelength. i.e.



As the tension, force acted on vibrated string increase the number of segments decreases at constant frequency.

So, the tension force is inversely proportional to the number of segments (n).


Fourth; Comparisons

Compare between each of the following:

The constructive and destructive interference in sound

i- From the point of view of[the intensity of sound produced and the path difference].

ii-from the point of view of the occurrence condition.

iii-from the point of view of the path difference.



Comparison between constructive and destructive interference in sound.

1-Constructive interference 2-Destructive interference

1-occurrence Happens when a compression

coincide with a compression

and the rarefaction coinciding with

a rarefaction Happens when a compression coincide with a rarefaction

2-Sound intensity



3-The occurrence condition

Sound intensity increase and the two waves reinforce each other
(sound is heard) Sound intensity decreases and the two waves weaken each
other (no sound heard)


It is occur when the path-difference between the two waves equals

,2 ,3 ,. . . . . . (n)λ

It is occur when the path-difference between the two waves equals



Fifth; practical experiments

1- By using the vibration produced from two neighboring sound
source; show with diagram the formation of the interference patterns
between two sound waves ,mention the necessary conditions then, Explain
why the intensity of sound increase at some points and decreases at the
other.

(Demonstration of the interference phenomenon )

By using vibration produced from two neighboring sound sources

1)Set up two loudspeakers( S1 and S2)emitting sound waves of the same constant frequency and amplitude as shown in fig.

2)When the two sources start to oscillate they produce
longitudinal sound waves propagated in the form of continuous
compressions arcs and continuous rarefaction arcs (dotted arcs).

3)The two waves superposing with each other to produce a steady
interference pattern as shown in fig., At certain points we can hear
the sound that becomes alternately louder and quieter as waves from the
two speakers reinforce then cancel each other out..

The demonstration:

-When the compressions of the two sources are combining together
as well as the rarefactions, the two waves reinforce each other .That is
known as Constructive Interference in this case sound can be heard
louder

The necessary condition for that is the path difference between
the two waves should equals 0, , 2 , m ,… etc, where m is an integer
value and is the wave length.

B)When the compression meets the rarefaction the two waves cancel
each other that is known as Destructive Interference therefore, sound
becomes quieter or vanish that occurs when the path difference between
the two waves equals , 1 , …(m+ ) , where m is an integer value and
is the wave length.


Sixth; Important proves


1 -PROVING THE RELATION ( )

Consider (L) is the length of the string and vibrated to form (n) segments.

Then

the length of each segment=

the length of each segment=

The velocity of the string given by

V =



Where FT : is the tension force in Newton

m: is the mass per unit length.


Prove that the ratio between the frequency of the fundamental tone and their harmonic in string is 1: 2: 3


The ratio of the frequencies of the fundamental (first harmonic) tone to the associated harmonics (overtones) is (1 : 2 : 3)


Since

When , n=3 When , n=2 When , n=1


The ratio between the frequencies is , 1 : 2 : 3


seventh; Selected problems


A vibrating string emits a tone related to the relation



Where