physics 2 exam

What are the 3 bigness?

Amplitude

Power

Intensity

What do the 3 bigness parameters describe?

Size, Magnitude or strength of a wave

They describe how “big” or “powerful” the wave is but they do not describe the speed or frequency

Output Power” Button

On the ultrasound machine, when the sonographer turns up the output power, it sends stronger sound waves into the body.

Increases Intensity, the echoes come back brighter, and the image looks clearer 

But we have to be careful — too much intensity can heat tissue, so we keep it at safe levels.

Relationship between Intensity and Amplitude 

Proportional: 

When the amplitude is doubled,  the intensity increases to 4 times the original value 

In other words, when the amplitude is decreased by a factor of 2, the intensity is decreased by a factor of 4(quadruple)

What relationship do the 3 parameters have?

They are directly related. If one of these parameters increases, the other 2 do too.

Relationship of intensity and power?

It is proportional; If power is doubled, the intensity is doubled

Both amplitude and power are parameters that describe?

Describe the size or magnitude(how big or how strong something is) of the wave.

magnitude = size, amount, or strength of something

How are power and amplitude related?

Power is proportional to amplitude

When power increases, so does amplitude. Similarly, when power decreases, amplitude decreases

When you turn down power?

When you turn down the power, you are turning down the strength of the reflections and also decreasing the bio effects.

Is amplitude adjustable?

 

Yes, with overall gain or TGC(time gain compensation)

Increase the brightness of the image 

• The sound leaves the probe at one strength (one amplitude).

• As it travels deeper, it gets weaker (attenuation).

• The sonographer adjusts gain to make up for that loss so the image looks even from top to bottom.

Because deeper echoes come back weaker, the sonographer can adjust the amplitude of the returning echoes on the screen.

This adjustment is called “gain.”

• Increasing gain makes the returning echoes appear brighter — like turning up the volume so you can “hear” faint echoes better.

• It doesn’t make the sound in the body stronger, it just makes the display stronger (so you can see the echoes more clearly).

what is amplitude?

• Amplitude(bigness of wave) is the strength or height of the sound wave — how strong it is when it leaves the transducer.

• It’s like how loud your voice is when you first speak.

• Determined by the source

• Adjustable yes

• Units=Pascals,dB

When discussing the relationship between the 3 bigness the word squared always follows the word?

Amplitude

Power is related to the Amplitude squared

Intensity is related to the Amplitude squared

Power is related to the intensity

REMEMBER:AMPLITUDE SQUARED

Wavelength

Is the distance or length of one complete cycle

Units: mm, Meters

Wavelength is the only parameter that is determined by both the source and the medium

Wavelength refers to distance

Wavelength and period are differentiated by?

their units

wavelength has units of distance(mm, distance)

period has units of time(seconds ,us ,time)

What is the relationship between wavelength and frequency?

Wavelength and frequency are inversely related.

As frequency increases, wavelength decreases.

The lower the frequency, the longer the wavelength

Why is wavelength important in diagnostic ultrasound?

It plays a very important role in image quality.

Shorter wavelengths are created by higher frequency sound. This usually produces higher-quality images with greater detail.