• QUESTIONS BEFORE LECTURE 29

now think about these

• Be very clear how scattering and spectroscopy let us "see" atoms and their constituents. What apparatus or steps does each of these techniques require?
• What type of particle has Brownian motion? How is it evidence of atoms?
• What does "kinetic" in Kinetic Theory of Gases refer to? How is it evidence of atoms?
• What happenes to air pressure when temperature drops? rises? why?
• How does a Scanning Tunneling Microscope work? The explanation will tell you how it got its name. There's one right under the lecture hall where I give 107 lectures if you ever want me to show it to you.
• How did Becquerel know he had a new effect (radioactivity)? (He was looking for sunlight in, x-rays out. What did he find?)
• J. J. Thomson could only get the charge-to-mass ratio of an electron, which was 2000 times as big as for a proton. What facts from his experiments with the electrons led him to the correct guess that the electron's mass is small, not its charge big? There are between 2 and 4 answers to this.
• What's a plum pudding atom? A planetary atom? What is good and what is bad about the planetary model as seen in classical physics?
• What force was Rutherford dealing with in his experiment to discover the nucleus?
• A scattering experiment has a beam, a target, and a detector for what comes out. What were each of these in Rutherford's experiment?