HW

How do batteries work?  Find out and write about it in your notes.

HW - electric fields (for Thurs/Fri)

Draw electric fields for each of the following:

a.  big hunk of negative charge
b.  big hunk of positive charge
c.  negative charge and positive charge separated by a short distance
d.  positive charge and identical positive charge separated by a short distance
e.  negative charge and identical negative charge separated by a short distance

Play around with this.  It should run on most machines:

http://phet.colorado.edu/en/simulation/charges-and-fields

Place charges on the screen and click "show E-field" and "direction only".

Start simple and go crazy.

If your computer will allow, these are great:

http://www.falstad.com/emstatic/

http://www.falstad.com/vector3de/

HW

For Tuesday/Wednesday class;

Look up (in physics classroom or elsewhere) information about electric fields.

If your computer allow it, play around with this applet:

http://www.falstad.com/emstatic/

Coulomb's law HW

1.  What are each of the quantities in the Coulomb's law equation, and what are their units?

2.  a.  Calculate the force that exists between two clusters of charge (each 10 micro coulombs), 0.1-m apart.  The prefix "micro" means x 10^-6.
b.  Is this force attractive or repulsive?  How do you know?

3.  If you have a cluster of charge that is 5 C in magnitude, how many protons is this?

4.  Thinking about the inverse square law - if the distance between two charges is changed to five times the original distance, what exactly happens to the force between them (compared to the original force)?

5.  If the distance between two charges is changed to half the original distance, what exactly happens to the force between them (compared to the original force)?

6.  The radius of a typical Hydrogen atom is 53 pm (5.3 x 10^-11 m) -- the distance between a proton and electron in "orbit" around it.  What is the force between these two particles?

HW

Find out something about:

Coulomb's law (including the equation)
Electric fields

HW to turn in Thursday (F) or Friday (A)

1.  Find out about a few examples of how holography is used today.  Or if you're feeling ambitious, suggest some uses for it.

2.  Diffraction question

You are sending light through a diffraction grating that has 300,000 slits/openings per meter.  You aim a blue laser at it (wavelength = 475 x 10^-9 m).  The laser and grating is 1-m from a wall.  Find:

a.  the value for d (the distance between the slits)
b.  the diffraction angle for a first order (n = 1) image
c.  the distance between the central image (n = 0) and the first (n = 1) image.  Use trig here.
d.  Draw this situation.
e.  How many dots would you see on the wall?
f.  If you used a red laser, would the dot spacing change?  If so, how?

HW

F block - come to class with some type of definition of "charge" (the electrical type).

A block - come to class with some understanding/definition of holography (if you haven't yet done this).  Also, look into x-ray diffraction, if you have not yet done this.

Happy weekend!

late update (for F block).

For Friday's F-block class -- Look into x-ray diffraction a bit more.  And also find out a little about holography.  Sorry for the delay.

HW

Please do a little reading about light diffraction.  Find out what it is, and if possible, find a mathematical expression that represents it.