Physics CH 9 powerpoint & notes

Constructive and destructive interference results in a beam that's shaped like:

• a triangle

• an inverted triangle

• a wave

• an hourglass

Small sound sources create ____ shaped wavelets.

• w

• v

• s

• ~

The _____ shape of the sound beams is produced by the interference of these tiny wavelets.

• triangle

• inverted triangle

• wave

• hourglass

____ beams create better images.

• wide

• smooth

• narrow

• v-shaped

As sound travels, the width of the beam ____.

• stays the same

• changes

• amplifies

Focal depth is determined by:

• frequency

• near zone length & transducer diameter

• spatial pulse length & frequency of the sound

• transducer diameter & frequency of the sound

focal depth =

• mm x MHz

  ---

  6

• cm x MHz

  ---

  6

• mm x MHz

  ---

  4

• mm x Hz

  ---

  4

If a crystal is 30 mm in diameter and the OF is 4 MHz, the focal depth is:

• 120mm

• 50mm

• 20mm

• 25mm

If a crystal is 15 mm in diameter and the OF is 4 MHz, the focal depth is:

• 10mm

• 50mm

• 20mm

• 25mm

Smaller diameter crystals produce beams that ____ in the far field

• converge

• reflect

• diverge

• refract