Ultrasonic level 1

Question 1

The cable that connects the ultrasonic instrument to the search unit is specially designed so that one conductor is centred inside another. The technical name for such a cable is?

Answer 1

Coaxial Cable

Question 2

The process of comparing an instrument or device with a standard is called:

Answer 2

Calibration

Question 3

A material used between the face of a search unit and the test surface to permit or improve the transmission of ultrasonic vibrations from the search unit to the material being tested is called?

Answer 3

A couplant (Reduce the impedance mismatch)

Question 4

Ultrasonic testing of material where the search unit is in direct contact with the material being tested may be?

Answer 4

All of these: Straight beam testing, surface wave testing and angle beam testing.

Question 5

The indication on the cathode ray tube (CRT) which represents the far boundary of the material being tested is called?

Answer 5

Back wall echo or aka The back surface reflection

Question 6

When an ultrasonic beam passes through the interface between two dissimilar materials at an angle, a new angle of sound travel takes place in the second material due to?

Answer 6

refraction

Question 7

The amount of beam divergence from a crystal is primarily dependent on the?

Answer 7

Frequency and crystal size

Question 8

Which of the following materials of the same alloy is most likely to produce the greatest amount of sound attenuation over a given distance.

Answer 8

A course-grained casting (Grey casting)

Question 9

A test method employed two separate search units on opposite surfaces of material being tested is called?

Answer 9

Through-transmission testing.

Question 10

The boundary between two different materials which are in contact with each other is called?

Answer 10

An interface

Question 11

When the motion of the particles of a medium is parallel to the direction of propagation, the wave being transmitted is called a.

Answer 11

Longitudinal wave

Question 12

“25 million cycles per second” can also be stated as?

Answer 12

25MHz

Question 13

A term used in ultrasonics to express the rate at which sound waves pass through various substances is?

Answer 13

Velocity

Question 14

In an A-scan presentation, the horizontal base line represents?

Answer 14

The Elapsed time or distance

Question 15

In ultrasonic testing. a liquid coupling medium between the crystal surface and the part surface is necessary because?

Answer 15

An air interface between the crystal surface and the part surface would completely reflect the ultrasonic vibrations.

Question 16

Sound waves of a frequency beyond the hearing rang of the human ear are referred to as ultrasonic waves or vibrations, and the term embraces all vibrational waves of frequency greater then approximately?

Answer 16

20 000Hz

Question 17

The velocity of sound waves is primarily dependant on?

Answer 17

the material in which the sound is being transmitted and the mode of vibration.

Question 18

The primary purpose of reference blocks is to?

Answer 18

Obtain a common reproducible signal.

Question 19

The angle of incidence is:

Answer 19

Equal to the angle of reflection.

Question 20

The depth of a discontinuity cannot be determined when using the?

Answer 20

Through-transmission testing method. (2 probe method)

Question 21

The interference field near the face of a transducer is often referred to as the?

Answer 21

Fresnel Zone (NZP)

Question 22

The product of the acoustic velocity of sound in a material and the density of the material is the factor that determines the amount of reflection or transmission of ultrasonic energy when it reaches an interface. This term is called?

Answer 22

Acoustic impedance (Z=PxV)

Question 23

The formula used to calculate the angle of reflection with a material is called?

Answer 23

Snells law

Question 24

In a material with a given velocity, when frequency is increased the wavelength will?

Answer 24

Decrease

Question 25

Which is a plot of signal amplitude versus time?

Answer 25

an A-Scan display

Question 26

As the grain size increases, its principal effect is ultrasonic testing is on the?

Answer 26

Attenuation

Question 27

In straight beam pulse echo testing, a discontinuity with a rough reflecting surface perpendicular to the incident wave will have what effect on the detected signal in comparison to a smooth flat bottom hole of the same size?

Answer 27

Decrease it

Question 28

Ultrasonic vibrations are commonly used to?

Answer 28

Examine materials for discontinuities, for thickness and for mechanical properties (All of them)

Question 29

Which of the following has the longest Fresnel Zone. (NZP)

1. 13mm diameter 1MHz
2. 13mm diameter 2.25 MHz
3. 28.5mm diameter 1 MHz
4. 38mm diameter 2MHz

Hint: V = diameter squared, divided by 4 x wavelength

Answer 29

4. 38mm diameter 2MHz

Remember:
V = diameter squared, divided by 4 x wavelength

Question 30

In immersion testing, a wetting agent is added to the water to?

Answer 30

Help eliminate the formation of air bubbles

Question 31

The variable in distance amplitude calibration block construction is the?

Answer 31

Metal distance above the drill hole

Question 32

In immersion testing, when the sound beam strikes a concave surface, the sound beam tends to?

Answer 32

Converge

Question 33

Most ferrous and non-ferrous welds may be ultrasonically tested using a frequency range of ?

Answer 33

1 - 2.25 (check this answer)

Question 34

In selecting a suitable couplant, which of the following characteristics would NOT affect the selection?

1. Mode of propagation.
2. material surface finish & temp
3. operating frequency of the transducer
4. chemical properties of the couplant

Answer 34

Mode of propagation desired.

Question 35

Meaning of: ‘Critical angle’

Answer 35

The incident angle of the ultrasonic beam beyond.

Question 36

‘Surface Wave’ also known as?

Answer 36

Rayleigh waves

Question 37

When measuring a ‘Curved Surface’.

you would use Single crystal or twin crystal?

Answer 37

Small diameter probe - twin crystal prob = more surface area