Agenda

• Today– Chapter 24 (Finish Fri & Start 25)

• HMWK Due Fri

• Return Quiz Friday

• Reading– Finish ch. 24 by Friday– Skim 25 (at least last page) Friday– Read 25 by Monday

Simplest Form: || Plate

Apply Voltage Across Parallel Plates

V = EdE (plate) = E (Between) = = Q/AInfinite just approximationE = Q/(A0)V = EdV = Qd / (A0)

Simplest Form: || Plate

Apply Voltage Across Parallel Plates

V = Qd / (A0)Capacitance = Ability to store Charge from VQ = V C [C is capacitance]V = Q / C|| plate: C = A0/dExamine parametersGeometric & material only, no field dep.

Energy Storage: Capacitor

• Consider how much energy it takes to move charges from one plate to another

• “Assemble” Charges

• Work done in moving charges stored as Potential Energy

Energy Storage: Capacitor

0

0

2

2

Q

Q

QV

C

W VdQ

W VdQ

QW dQ

C

QW

C

Can Apply Top Equation to BottomMix & Match, Q,V,CAs usual, ½ Integration

Other Geometries

• Spherical, other all have different formulas for capacitance

• Universal:– C depends only on dielectric & geometry– Q = VC– PE = Q2/2C

|| Plate CombinationsC = A/d

How does capacitance change if we go from One…

|| Plate CombinationsC = A/d

How does capacitance change if we go from One…To Two capacitors attached like this?

Does V Change?Does Q Change?Depends on outsideCapacitance internal!

|| Plate CombinationsC = A/d

How does capacitance change if we go from One…To Two capacitors attached like this?

Is Same as…

|| Plate CombinationsC = A/d

How does capacitance change if we go from One…To Two capacitors attached like this?

Is Same as…Twice the AreaTwice the capacitance..

|| Plate CombinationsC = A/d

How does capacitance change if we go from One…To Two capacitors attached like this?

Comment on the charge at these 2 points?

Must be Equal & opposite?How about must be same?So Effective Capacitor looks like….

|| Plate CombinationsC = A/d

How does capacitance change if we go from One…To Two capacitors attached like this?

Effective Distance between plates doubledCapacitance halved

Series & ParallelFirst Look

Series CapacitorsCapacitance Reduced

Parallel CapacitorsCapacitance Increased

Future

• Next Week

• Monday: Ch.25

• Need to Miss Wed?– Class Canceled or Sub?– Sub = Quiz Wed, Lecture & Lab Tues– No Sub = Skip Lab, Quiz & Lecture Tues

• Quiz on Problem from CH. 21-23

What?Alternative Energy Research

• New (hopefully) multi-year investigation• Exploring new materials for use in hydrogen

energy storage and solar power– Chemistry & Chemical Bonding– Nanoscience measurement and analysis– Materials Science– Engineering: Design, Implementation, and

Development– Integration with future and current teachers– Integration with science policy

Who?

• Students interested in engineering– Electrical, materials, systems– Good with hands, not afraid of electricity– Willing to learn CAD design

• Students interested in Experimental Science– Chemistry/Physics Mixture– Materials grown @ UNI, Nanostructures formed here– Analysis (SEM, AFM, STM) & Feedback– Understand, Predict, Create Novel materials

• Students interested in Science Education– Perform Experimental Research– Work with junior high & high school teachers– Develop curriculum & research

How Many?

• Looking for another 2 or 3 students– Summer & perhaps beyond

• Need: AFM Operator

Nanoscale ObjectsSeveral atoms high (<10)Template for High Efficiency Solar Cell

How Many?

• Looking for another 2 or 3 students– Summer & perhaps beyond

• Need: SEM/EDX Operator?

Microstructure CharacterizationChemical Information Also

How Many?

• Looking for another 2 or 3 students– Summer & perhaps beyond

• Need: UHV /Elecronics Engineer– Begin by implementing, Work towards Design

Modeling

• Work towards understanding of fundamental science

• Experience with programming a +

• Understand phenomena