Knowledge about LC oscillator circuit, expert in!

1. How many times does the direction of the current change during a cycle?

Or once, if the current is 0 at the start of the cycle.

Or twice, if the current is not 0 at the start of the cycle.

So it's a total word game, no need to get hung up on it.

As for why it should be twice instead of once, think about how many times the direction of the current changes in 10 cycles.

If the current is 0 at the start of the cycle, then it changes 19 times.

If the current was not 0 at the start of the cycle, then it changed 20 times.

And so it is clear that the number of changes and the number of cycles is a factor of two, not one.

As for the one time difference, it's just the difference between y=2n and y=2n-1, which is the difference in the initial value.

2. It takes one-half of a cycle to change from all magnetic field to all electric field.