Transcript Slide 1
Classical _______________physics particle 1. Matter is a____________________ wave 2. Light is a _________________. This is "everyday" physics that deals with objects that are relatively large atoms 1. _____________ bigger than _____________ slow 2. _____________ v << _____ c Einstein _______________ modified classical physics so that it would give more accurate results when speeds were close to c gravity _______________________________ and for________________. Special His theories are called the ________________ and General Relativity ________________ Theories of _________________________ . Modern _______________ physics modified physics to deal with atoms tiny objects _________________________ on the scale of ___________ . According to this theory: 1. Matter can act like a___________________________. particle or a wave 2. Light can act like a___________________________. particle or a wave wave Ex: Light in the classical view acts like a ___________ amplitude whose _________________ determines its energy: brighter _______________ energy more____________ photoelectric Ex: The ___________________ effect showed that light can act like a ______________________ . particle shine light “photo…” electrons e- zinc “…electric” color of light brightness of light how many electrons were ejected from the zinc and with what KE red dim no e- red bright no e- violet dim a few e- with lots of KE violet bright lots of e- with lots of KE Duality: wave particle Einstein _____________________________ for a paper that won a Nobel Prize explained the photoelectric effect by assuming light frequency particle acted like ______________. The higher its _______________ the greater the energy of the light particle. Bright light many consists of ___________ particles. dim red _______________ light: bright red ________________light: dim violet ________________light: bright violet ________________light: low 1_______ energy particle cannot eject an enone of these many low _______ energy particles could eject an ehigh energy particle 1_______ can eject 1 eeach of these many high energy particles ________ could eject an e- quantum The ______________ (basic unit) of electromagnetic energy (light) is called a _______________ . It has no photon energy momentum . mass, but carries ______________ and ________________ Its energy is given by: Eph = where h= = Ex: What is the relationship between Eph and f? Eph f What quantity does the slope of the line? See page 1 of Reference Tables Page 1: top quantum The ______________ (basic unit) of electromagnetic energy (light) is called a _______________ . It has no photon energy momentum . mass, but carries ______________ and ________________ Its energy is given by: Eph = where h= = Ex: What is the relationship between Eph and f? hf Planck's constant 6.63 x 10-34 J·s Eph f What quantity does the slope of the line? Eph/f = ? h Ex: What is the relationship between Eph and l? Start with the equation: v = fl c = fl Substitute c in for v: Solve for f: f = c/ l Substitute in the equation for Eph= hf Eph= hc/l Ex: What is the relationship between Eph and l in graph form? Eph l The greater the wavelength, the ___________ the energy. Ex: What is the relationship between Eph and l? Start with the equation: v = fl Substitute c in for v: c = fl Solve for f: f = c/ l Substitute in the equation for Eph= hf Eph= hc/l Ex: What is the relationship between Eph and l in graph form? Eph l less The greater the wavelength, the ___________ the energy. Ex: Find the energy of a blue light photon in joules. Eph = hf = hc/l = (6.63 x 10-34 J·s) (???) Convert the answer to electronvolts (eV). page 1 of RT: 1 eV = ________________ J Choose f = 6.5 x 1014 Hz Ex: Find the energy of a blue light photon in joules. Eph = hf = hc/l = (6.63 x 10-34 J·s) (6.5 x 1014 Hz) = 4.3 x 10-19 J Convert the answer to electronvolts (eV). page 1 of RT: 1 eV = ________________ J Page 1: top Ex: Find the energy of a blue light photon in joules. Eph = hf = hc/l = (6.63 x 10-34 J·s) (6.5 x 1014 Hz) = 4.3 x 10-19 J Convert the answer to electronvolts (eV). See page 1 of RT: 1.6 x 10-19 J 1 eV = ________________ Eph = 4.3 x 10-19 J x Eph = 2.7 eV _______1 eV_______ 1.6 x 10-19 J Quantum electromagnetic _____________ theory - ____________________ energy matter is emitted from and absorbed by _______________ discrete "packets" in _____________ amounts or ________________ . Discrete ( ______________ means "separate, individual pieces.") Ex: absorption _______________ of a photon before: atom emission Ex: _____________ of a photon before: atom after: atom has ______ more energy after: atom has less _______ energy Compton Ex The ____________Effect: X-rays scatter off electrons. before collision: v=c 0 e- at rest KE =____ x-ray _______ photon now has KE e- ____________ after collision: c The scattered photon now has less energy. _______ less So its f is _______ and its l is longer ______________ momentum energy Both _________________and ______________ are conserved. particle In sum, light can act like a __________________ or like a ____________ . Which one it acts like depends on wave the situation. When light interacts with.. light … __________ , it acts atoms … ___________ , it acts wave like a _________________ particle like a __________________ Examples: interference 1/ __________________ diffraction 2/ __________________ Examples: absorption 1/ __________________ emission 2/ __________________ collisions 3/ __________________ Even when it is described as a photon, we still frequency use __________ wave properties such as _______________ wavelength and _________________ to describe it. Electron charge: In 1909, Millikan sprayed drops of oil electric ________ into an _______________ field E. qE Fe =___ oil drop mg Fg =_____ By suspending the oil drop then letting it fall, he was able to discover that the oil drops always carried integer multiple an ___________________________ of the fundamental charge 1.6 x 10-19 C quantum = ______________________ (the ______________ of charge). which is the charge on 1 _____________ or _____________ . electron proton quantized Charge is __________________ .