سوال ۲۶ کنکور ارشد فیزیک ۱۴۰۱

PART C: Reading Comprehension — PASSAGE 3

Paragraph 1. Heinrich Hertz’s doctoral dissertation focused on James Clerk Maxwell’s theories of electromagnetism. Maxwell worked in mathematical physics until his death in 1879 and formulated what is now known as Maxwell’s Equations. They describe, through mathematics, the functions of electricity and magnetism. He also predicted the existence of electromagnetic waves.

Paragraph 2. Hertz’s work focused on that proof, which took him several years to achieve. He constructed a simple dipole antenna with a spark gap between the elements, and he managed to produce radio waves with it. Between 1879 and 1889, he did a series of experiments that used electrical and magnetic fields to produce waves that could be measured. He established that the velocity of the waves was the same as the speed of light, and studied the characteristics of the fields he generated, measuring their magnitude, polarization, and reflections. Ultimately, his work showed that light and other waves he measured were all a form of electromagnetic radiation that could be defined by Maxwell’s equations. He proved through his work that electromagnetic waves can and do move through the air. In addition, Hertz focused on a concept called the photoelectric effect, which occurs when an object with electrical charge loses that charge very quickly when it is exposed to light, in his case, ultraviolet radiation. He observed and described the effect, but never explained why it happened. That was left to Albert Einstein, who published his own work on the effect. He suggested that light (electromagnetic radiation) consists of energy carried by electromagnetic waves in little packets called quanta.

Paragraph 3. Hertz’s studies and Einstein’s later work eventually became the basis for an important branch of physics called quantum mechanics. Hertz and his student Phillip Lenard also worked with cathode rays, which are produced inside vacuum tubes by electrodes.

26- Which of the following statements is true?