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0 Exakte Antworten 0 Text Antworten 184 Multiple Choice Antworten
Fenster schliessen

1.The velocity of propagation of the sound wave in an elastic medium is:

a)Proportional to the medium’s density

b)Inversly proportional to the volume elasticity module (E)

c)Proportional to the volume elasticity module

d)Proportional to the square root of the volume elasticity module

e)Proportional to the square root of the medium density

Fenster schliessen

2.Acoustic pressure is :

a)A measure of loudness

b)Is equal to the atmospheric pressure

c)Assuming its highest values at 3000Hz

d)Equal to the difference between actual value of pressure and the pressure value in the undisturbed (by sound) medium

e)Is the value of pressure exerted specifically at the tympanic membrane

Fenster schliessen

3.Acoustic impedance is defined as:

a)The product of medium density(p) and sound velocity(c)

b)Is the electrical impedance of the medium in which sound propagates

c)Is the measure of mechanical resistance of the ear system to the sound passing through it

d)Is a measure of sound inhibition by the ossicles in the middle ear

e)The extent of amplitude decay of the sound wave when penetrating the medium

Fenster schliessen

4.The sound wave travels within the medium M1 and enters the medium M2 crossing the interface between these two media. The acoustic impedances for M1 and M2 are 4.5kg*m2s and 1.5kg*m2s, respectively. Indicate the percentage of sound reflected at the interface:

(M1-M2/M1+M2)´2 or R= ( (Z1-Z2)/(Z1+Z2) )2

a)45%

b)15%

c)50%

d)75%

e)25%

Fenster schliessen

5.Radiopharmaceuticals (radiotracers) are NOT used in:

a)scintigraphy

b)computed tomography (CT)

c)positron emission tomography (PET)

d)single-photon emission computed tomography (SPECT)

e)magnetic resonance imaging (MRI)

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6. The fact that lenses have different focal points for red and violet light is…(called?):

a)chromatic aberration

b)spherical aberration

c)astigmatism

d)diffraction

e)refraction

Fenster schliessen

7.Find a true sentence describing fluorescence:

a)fluorescence has longer lifetime than phosphorescence

b) fluorescence has shorter lifetime than phosphorescence

c)fluorescence spectra of the substances are blue shifted in comparison…(to?) absorption spectra

d)fluorescence is a transition between states of different multiplici..(ty?)

e)fluorescence is a transition between singlet and triplet state

Fenster schliessen

8.The number of orientations that magnetic moment of proton c…. External magnetic field is:

a)infinite

b)two

c)three

d)four

e)any nr between 1 and 10