Прочитайте текст и определите, какой из заголовков соответствует тексту
By applying a potential difference (voltage) from a battery or other source between the plate and cathode of a diode, an electric field is established within the tube. The lines of force of this field always extend from the negatively charged element to the positively charged element. Electrons, being negative electric charges, follow the direction of the lines of force in an electric field.