The Physics of Waves: Light Waves, Sound Waves and Ultrasound
When ultrasound strikes the boundary between two different body tissues, the amount of reflection that will occur is proportional to the difference in what?
The speed of sound in the tissues
The density of the two tissues
Elasticity in the tissues
Impedance between the two tissues
Impedance between the two tissues
The impedance depends on the speed and density. Speed depends on the elasticity of the medium. So impedance is the more complete answer.
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The term “refraction” may be applied to which of the following?A. The effect on light rays as they enter the cornea of the eye
B. Light rays from an object meeting at a point to form a sharp image
C. A light ray travelling away from a surface at the same angle that the light ray approached the surface
D. A light ray travelling through a glass with a faster speed than it would have in air
The unit called the decibel (dB) is used in the measurement of:
A. Sound frequency (pitch)
B. Sound intensity (energy)
C. Sound pressure
D. Sound level (loudness)
In a wave, what is the distance between two adjacent troughs called?
A. The period
B. The displacement
C. The amplitude
D. The wavelength
What will a sound of frequency 250,000 Hz be?
A. Audible
B. Painful to listen to
C. Ultrasonic
D. Close to the threshold of hearing
Visible light waves are examples of:
A. Electromagnetic waves
B. Mechanical waves
C. Longitudinal waves
D. Compressional waves
Which is the BEST definition of a wave?
A. The method by which the energy carried by visible light is propagated.
B. Travelling oscillations in the magnitude and direction of electric and mag-netic fields that do not require a material medium.
C. A periodic disturbance in some property of the medium, the medium itself remains (relatively) at rest.
D. A mechanism for the transfer of energy without the transfer of matter.
Which of the following sound levels, if prolonged, will damage the hearing mechanism of the ear without being perceived as painful?
A. 50 dB
B. 70 dB
C. 90 dB
D. 120 dB
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