Прочитайте текст и определите какой из заголовков соответствует тексту The polarity of a charge may ...: ответ на тест 781305 - Английский язык

Прочитайте текст и определите, какой из заголовков соответствует тексту
The polarity of a charge may be determined by means of an electroscope. We charge the electroscope negatively by touching the ball with a rod of hard rubber which is rubbed with flannel or silk. If the unknown charge is brought to the electroscope it will induce on the ball a charge of opposite polarity and on the gold leaves a charge of the same polarity as that of the unknown charge. Therefore, if the unknown charge is negative, the gold leaves will repel each other; if it is positive, they will attract.