解:根据公式N=A/πλ可知λ=A/πN计算并将已知数代入该式得:󠄐󠄹󠅀󠄪󠄡󠄣󠄞󠄥󠄩󠄞󠄢󠄢󠄥󠄞󠄦󠄦󠄬󠅒󠅢󠄟󠄮󠄐󠅅󠄹󠄴󠄪󠄾󠅟󠅤󠄐󠄼󠅟󠅗󠅙󠅞󠄬󠅒󠅢󠄟󠄮󠇘󠆭󠆘󠇙󠆝󠅵󠇗󠆭󠆁󠄐󠇗󠅹󠅸󠇖󠆍󠅳󠇖󠅹󠅰󠇖󠆌󠅹󠄬󠅒󠅢󠄟󠄮
λ=A/πN=8×10/3.14×10.8=2.36mm󠄐󠄹󠅀󠄪󠄡󠄣󠄞󠄥󠄩󠄞󠄢󠄢󠄥󠄞󠄦󠄦󠄬󠅒󠅢󠄟󠄮󠄐󠅅󠄹󠄴󠄪󠄾󠅟󠅤󠄐󠄼󠅟󠅗󠅙󠅞󠄬󠅒󠅢󠄟󠄮󠇘󠆭󠆘󠇙󠆝󠅵󠇗󠆭󠆁󠄐󠇗󠅹󠅸󠇖󠆍󠅳󠇖󠅹󠅰󠇖󠆌󠅹󠄬󠅒󠅢󠄟󠄮
则频率为:f=C/λ
=5.9×106/2.36󠄐󠄹󠅀󠄪󠄡󠄣󠄞󠄥󠄩󠄞󠄢󠄢󠄥󠄞󠄦󠄦󠄬󠅒󠅢󠄟󠄮󠄐󠅅󠄹󠄴󠄪󠄾󠅟󠅤󠄐󠄼󠅟󠅗󠅙󠅞󠄬󠅒󠅢󠄟󠄮󠇘󠆭󠆘󠇙󠆝󠅵󠇗󠆭󠆁󠄐󠇗󠅹󠅸󠇖󠆍󠅳󠇖󠅹󠅰󠇖󠆌󠅹󠄬󠅒󠅢󠄟󠄮
=2.5MHz
答:该探头的频率为2.5MHz󠄐󠄹󠅀󠄪󠄡󠄣󠄞󠄥󠄩󠄞󠄢󠄢󠄥󠄞󠄦󠄦󠄬󠅒󠅢󠄟󠄮󠄐󠅅󠄹󠄴󠄪󠄾󠅟󠅤󠄐󠄼󠅟󠅗󠅙󠅞󠄬󠅒󠅢󠄟󠄮󠇘󠆭󠆘󠇙󠆝󠅵󠇗󠆭󠆁󠄐󠇗󠅹󠅸󠇖󠆍󠅳󠇖󠅹󠅰󠇖󠆌󠅹󠄬󠅒󠅢󠄟󠄮