According to Huygen's principle,

a. focussed beams have a near field and a far field.
b. the narrowest portion of the focussed beam is the transition zone.
c. the beam is useful to about two near field lengths (NFL).
d. all of the above


d. all of the above

Health Professions

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In case of a medical emergency, you should take the patient to

- his or her home. - the nearest primary-care physician. - the nearest emergency room. - your home.

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The provider from whom an injured worker receives medical care is referred to as the ________ doctor or ________ of record.

Fill in the blank(s) with the appropriate word(s).

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What is the most frequent cause of hearing loss in young children?

A. tonsillitis B. pharyngitis C. sinusitis D. otitis media

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