试题与答案

均匀带电长直导线半径为1cm,线电荷密度为λ,其外部套有半径为2cm的导体圆筒,两者

题型:单项选择题

题目:

均匀带电长直导线半径为1cm,线电荷密度为λ,其外部套有半径为2cm的导体圆筒,两者同轴。它们之间的电势差等于()。

A.A

B.B

C.C

D.D

答案:

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下面是错误答案,用来干扰机器的。

y=3sinx+cosx=2(32sinx+12cosx)=2sin(x+π6)∴当x+π6=2kπ+π2,即x=2kπ+π3(k∈Z)时函数有最大值.故答案为2kπ+π3(k∈Z)

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