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# ultrasound frequency help? watch

1. Can anyone help me with this question?

For a normal ultrasound scan, the waves travel at a speed of 1500m/s. For a detailed image, the wavelength should be no more than 1.0mm.

What frequency is needed?
2. Use v = f x lamda
3. (Original post by MathsAstronomy12)
Use v = f x lamda
i thought so and get a answer of 1.5*10^6 Hz but thought it was too big
4. (Original post by doctor_2_be)
i thought so and get a answer of 1.5*10^6 Hz but thought it was too big
Ultrasound freq > 20,000Hz so that's about right.
5. (Original post by MathsAstronomy12)
Ultrasound freq > 20,000Hz so that's about right.
ok,

thanx
6. (Original post by doctor_2_be)
i thought so and get a answer of 1.5*10^6 Hz but thought it was too big
No that's correct, most pregnancy scans use a frequency much higher so don't worry about it being too high. Remember that a sound wave with a frequency of 20000Hz or higher is classified as an ultrasound wave
7. (Original post by yasaminO_o)
No that's correct, most pregnancy scans use a frequency much higher so don't worry about it being too high. Remember that a sound wave with a frequency of 20000Hz or higher is classified as an ultrasound wave
thanx
ive recently been doubting everything i know so thought i'd double check
8. (Original post by doctor_2_be)
thanx
ive recently been doubting everything i know so thought i'd double check
No worries, is this BMAT prep? I had a similar meltdown the other day as well lol
9. (Original post by yasaminO_o)
No worries, is this BMAT prep? I had a similar meltdown the other day as well lol
no physics homeworl
10. (Original post by doctor_2_be)
no physics homeworl
11. (Original post by yasaminO_o)
dont worry about it, i wanted to go into medicine but then i developed a phobia to blood
12. do you know how i would do this?

A string is stretched and then the left end is oscillated up and down The 2 points on the string are labelled A and B. Rotate the vectors to show the direction of the wave velocity at the indicated points.

thanx

(Original post by yasaminO_o)
(Original post by MathsAstronomy12)
Ultrasound freq > 20,000Hz so that's about right.
Attached Files
13. wave vector.docx (245.0 KB, 55 views)
14. (Original post by doctor_2_be)
do you know how i would do this?

A string is stretched and then the left end is oscillated up and down The 2 points on the string are labelled A and B. Rotate the vectors to show the direction of the wave velocity at the indicated points.

thanx
Is it asking you to change the direction of the arrows to show the direction of the wave velocity? Because the diagram looks wrong to me. The arrows, if showing the direction of the wave velocity, should both be pointing to the right if the string is being oscillated from the left hand side. If you wanted to show the direction of the velocity of points A and B, the arrow at A should be pointing down and the arrow at point B should be pointing up.

Otherwise, if it's asking you to use special formulae, I have no clue, I only did Mechanics 1 lol
15. (Original post by yasaminO_o)
Is it asking you to change the direction of the arrows to show the direction of the wave velocity? Because the diagram looks wrong to me, the arrows, if showing the direction of the wave velocity, should both be pointing to the right if the string is being oscillated from the left hand side. If you wanted to show the direction of the velocity of points A and B, the arrow at A should be pointing down and the arrow at point B should be pointing up.

Otherwise, if it's asking you to use special formulae, I have no clue, I only did Mechanics 1 lol
yea, need to change the position of the arrows... thats what i thought but being the fact its to with vectors i wasnt 100% sure
16. (Original post by doctor_2_be)
yea, need to change the position of the arrows... thats what i thought but being the fact its to with vectors i wasnt 100% sure
No worries

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