Ultra Sound

Question 1

A block with a crack inside is scanned with a ultrasound.

Work out distance to the object (crack) reflecting the ultrasound.

• The speed of sound in air is 330 m/s
• time taken for reflection to return (s): 0.002

Answer 1

0. 002 x 330= 0.66 (distance traveled to and back from crack)
1. 66/2 = 0.33 m

=0.33

Question 2

Why is it important to calibrate the sensors on a submarine for sea water or for fresh water

Answer 2

• Sea water is dense so faster results

- wouldn’t give correct speed

Question 3

What would happen if the sea water settings were used to determine the depth of a fresh water lake?

Answer 3

It will think the waters deeper

-bigger number for sound

Question 4

What error would using the wrong settings introduce to a collection of data

Answer 4

Systematic error

Question 5

What is ultrasound

Answer 5

Sound waves above 20,000 Hz

Question 6

Why must the ultrasound beam be narrow and focused

Answer 6

Target specific areas

Question 7

Advantage of using gel on the skin during ultrasound

Answer 7

Allows sound waves to transmit into the body

Question 8

Why is the probe move around during the scan(ultrasound)

Answer 8

To create cross sections

Question 9

Why is a series of ultrasound pulses used instead of a continuous beam

Answer 9

Allow reflections back to the transducer (sir clapping)

Question 10

Why does an ultrasound of a beating heart keep changing

Answer 10

Because the heart moves/pulses

Question 11

Disadvantage of using gel on the skin (ultrasound)

Answer 11

Some waves are reflected due to changes in layers of thickness(skin)