This is a site for experienced and knowledgeable people.
There should be another site somewhere for * little school kids who are not learning anything in school.
We help many hobbiests understand a few complicated electronic theories here.
But the simplest of the basics of simple electricity are much different.
A multimeter is made to measure sine-waves at 50Hz and 60Hz only.
An oscilloscope can accurately measure the 45kHz unusual waveform across your resistor.