A parallel plate capacitor made of circular plates each of radius `R= 6.0` cm has a capacitance `c = 100pF`. The capacitor is connected to a `230 V AC` supply with a ( angular) frequency of `300 rad//s`
(a) What is the rms value of the conduction current ?
(b) Is the conduction current equal to the displacement current?
(c) Determine the amplitude of `B` at a point `3.0 cm` from the axis between the plates.
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Explanation

A radio can tune to minimum frequency , `v_(1)=7.5MHz=7.5xx10^(6)Hz`
Maximum frequency, `v_(2)=12MHz=12xx10^(6)Hz`
Speed of light, c`=3xx10^(3)m//s`
Corresponding wavelength for `v_(1)` can be calclated as:
`gamma_(1)=(c)/(v_(1))`
`=(3xx10^(8))/(7.5xx10^(6))=40m`
Corresponding wavelength for `v_(2)` can be calculated as:
`gamma_(2)=(c)/(v_(2))`
`=(3xx10^(8))/(12xx10^(6))=25m`
Thus, the wavelength band of the radio is 40m to 25m.