27.1.2 Observe and explain To help determine atomic structure, Philip Lenard sho

Question

27.1.2 Observe and explain To help determine atomic structure, Philip Lenard shot cathode rays (electrons) at a thin sheet of aluminum. He observed that electrons moved through the foil without any deflection. At this time physicists already knew that atoms are electrically neutral and contain several electrons. Electrons were known to have a very small mass, much smaller than the mass of the atom. An atomic model developed by J. J. Thomson included positive charge equally distributed within the atom with electrons embedded in it-like plums in a positively-charged plum pudding. Explain how this model accounted for Lenard's experiments.

Explanation / Answer

According to J.J thomson positive and negative chargea are equali distributed in atom like plum and pudding it means when electron is fired through aluminium atom it must not pass through the aluminium, it should be reflected back. But since it passes through the sheet withouth deflection it means most of the space is empty.

But he also knows that there are many electrons in atom electron must be reflected bak, but if energy of electron is very heigh than it will not reflect back by electrons present in the atom. Also electron must be attracted by positive chrges present in atom like Thomson's model. but electron beam do not deviate path means positive charge is not distributed equally in the atom.

Related Questions

Navigate

• Browse (All)
• Browse 2
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.