IOM 2019, Блиц — Задача 74

OLYMPIAD OF METROPOLISES, Moscow, September 2, 2019 · 2 септември 2019 г.

Условие

Graph of current I against time t: a sinusoid that starts at a positive value at t = 0, rises to a maximum, falls through zero to a minimum and rises again; the time axis is divided by dashed lines into intervals numbered 1, 2, 3, 4, 5.
Figure 2

There are two similar rings made of wire, which are isolated from each other. They share the same axis, as shown in figure 1. Now we do nothing to the right ring, but add a periodic current to the left ring. The relationship between this current and time is shown in figure 2. The direction of the arrow on the left ring is defined as positive direction. Please indicate all time periods when the interaction between these two rings manifests as attraction. Use the numbers marked in figure 2.

Two coaxial wire rings side by side on a dashed common axis; the left ring carries an arrow showing the positive current direction.
Figure 1

Решение

Внимание: Непълно решение

В архива няма официално решение на тази задача.

Оригинал в Архива: blitz-en-all-task-final.pdf