HW for Wednesday

1.  Think about this question.  If the charge of a proton is 1.6 x 10^-19 coulombs, how many protons would be required to make 1 coulomb of charge?  It's a big number, by the way.  (The answer is the same for -1 C and the number of electrons required.)

2.  Look up Coulomb's law and write a related equation.  Identify what the variables mean.

3.  What are the main differences between an electron and a proton?

4.  Look at the Standard Model chart, posted earlier - see if anything jumps out at you.

FYI

HW on charge

Questions to ponder.  Please write out your answers in your notebook.

1.  Write some type of definition of "charge".  It's ok to look something up, but try to formulate your own definition of charge first.

2.  Find the actual distance between an electron and a proton in a typical atom - it's ok to use hydrogen as your example.

3.  Are protons, electrons and neutrons are "fundamental"?  That is, can any of them be broken into something smaller?  If so, talk about it.

4.  Review the rotating 2x4 demonstration from today - why does the board rotate?

5.  What is the official standard unit for charge?  How is it defined?  This may be tough to put into words.  Try your best.

6.  How do the mass of proton, neutron and electron compare?  Look up their values, if that's helpful.

*7.  (If time allows.)  Look up the Heisenberg Uncertainty Principle.  How does it relate to the measuring of particles?  If you don't follow it, keep in mind that it was new and challenging enough to win Heisenberg a Nobel Prize (so don't feel bad).

for fun.

http://sploid.gizmodo.com/the-sum-of-1-2-3-4-5-until-infinity-is-so-1503066071/@caseychan

(Thanks, Kyle!)

http://geekdad.com/2014/01/1000000000000000000000-years/

pre-quiz homework

quiz practice

1.  Make sure you finish the diffraction (informal) lab for wavelength of laser light.  There may be a related question on the quiz.

2.  Speaking of which..... A 400 nm laser hits a diffraction grating (750 slits/mm).  The wall/screen is 2-m away from the grating.  Find:

a.  diffraction angle for a first order image
b.  distance between the central/primary (n = 0) image and the first order image

3.  Consider a 40-cm focal length mirror.  An object (5 cm in height) is 100 cm in front of it.  Find:

a.  image location
b.  magnification of image
c.  image characteristics
d.  Give the do(s) that would yield only virtual images.
e.  Give the do(s) that would yield NO images.

During the quiz day, I'll also ask you to write a short self-reflection/"what I've found interesting" paragraph.  This will be included in your semester grade report.  Feel free to start writing this now.  It needs to be emailed to me before the end of the week.  Thanks!

HW

Have a look at these pages:

Two things for homework.

Thing 1 - try these problems:

You have a lens with focal length 24 cm.  A plastic toy is located 50 cm from it.  Find the following:

a.  type of lens.  Recall that the sign of the focal length means something.

b.  location of image (di).  Use the lens equation.

c.  type of image (real or virtual).  Hint - a positive di means real; negative di means virtual.

d.  magnification of image (mag = - di/do)

e.  whether image is right-side up (positive magnification) or upside-down (negative magnification)

f.  whether image is larger (absolute value of magnification is bigger than 1) or smaller than object

g.  location(s) where you could move object and get NO image at all

h.  location(s) where you could move object and get only virtual image(s)

Thing 2 - Have a look at these pages.  Come to class with a definition of "diffraction" of light.

http://www.physicsclassroom.com/Class/light/u12l1a.cfm

http://www.physicsclassroom.com/Class/light/u12l1b.cfm