UNIT 9

The region from the transducer to the focus is called the:

Near zone

The region beyond the focus where the beam spreads out is called the:

far zone

The narrowest part of the beam is called the:

Focal point

The length from the transducer face to the focus is called the:

Near zone length (NZL)

Which factor increases the near zone length?

Higher frequency

what is the beam divergance and crystal diameter relationship?

inversely related

The Huygens principle explains that each point on a wavefront acts as:

A tiny circular wavelet

Which factor increases the near zone length (NZL)?

Larger transducer diameter

Which factor produces a narrower beam in the far field?

Larger crystal diameter

The near zone is also called the:

Fresnel zone

The far zone is also called the:

Fraunhofer zone

The focal zone is approximately how long?

half NZL

Which formula is used for near zone length (NZL)?

NZL = (D² x f) / 6

Which factor decreases near zone length?

Smaller diameter

If you double the crystal diameter, the near zone length will:

Quadruple

If you double the frequency, the near zone length will:

Double

Which combination produces the narrowest beam and least divergence?

Large crystal, high frequency

The focal depth is equal to:

NZL

A transducer has a 1 cm diameter and operates at 5 MHz, what is the NZL?

0.83 cm

A 2 cm diameter transducer operates at 5 MHz. Estimate NZL.

3.3 cm

The diameter of the transducer crystal itself is called the:

Aperture

The diameter of the beam at the transducer face is:

Equal to the aperture

what is the diameter at the focus?

half of the diameter at the transducer

The diameter of the transducer is 12 mm, and the NZL is 8 mm, what is the diameter of the sound beam at a depth of 16 cm?

12 mm

The diameter of the transducer is 12 mm, and the NZL is 8 cm, what is the diameter of the sound beam at a depth of 8 cm?

6 mm

The diameter of the transducer is 12 mm, and the NZL is 8 cm, at what depth is the focus?

8 cm