Ultrasonic Waves

Question 1

Speed of wave through material (m/s)

Answer 1

Velocity

Question 2

Distance between two wave peaks:

Answer 2

Wavelength

Question 3

Number of cycles per second (MHz)

Answer 3

Frequency

Question 4

Bending of the wave due to velocity change

Answer 4

Refraction

Question 5

Wave bouncing off an interface or defect

Answer 5

Reflection

Question 6

Loss of energy as sound travels through material

Answer 6

Attenuation

Question 7

Resistance to sound: (ρ = density)

Answer 7

Impedence

Question 8

Change from longitudinal to shear or surface wave

Answer 8

Mode Conversion

Question 9

What is Snell’s Law in ultrasonic testing?

Answer 9

Snell’s Law relates the incident angle and wave velocity in two materials:
(sin θ₁ / V₁) = (sin θ₂ / V₂)

Question 10

What happens when a wave passes from a fast to a slow medium?

Answer 10

It bends toward the normal (refraction angle decreases).

Question 11

What is mode conversion in ultrasonics?

Answer 11

It’s the splitting of a wave into different types (e.g., longitudinal to shear or surface wave) upon hitting a boundary.

Question 12

: What is the formula for wave velocity?

Answer 12

V = λ × f (Velocity = wavelength × frequency)

Question 13

What is acoustic impedance?

Answer 13

Z = ρ × V (Density × velocity). It affects reflection and transmission at material boundaries.

Question 14

Define attenuation in UT.

Answer 14

Loss of signal strength as sound travels through a material

Question 15

What kind of wave is generated when the incident angle exceeds critical angle?

Answer 15

Surface wave (e.g., Rayleigh wave) or total internal reflection occurs.

Question 16

What is the typical velocity of longitudinal waves in steel?

Answer 16

Approximately 5900 m/s.

Question 17

What is the typical velocity of shear waves in steel?

Answer 17

Approximately 3230 m/s.