Good Luck!
Exam 1 Review
Phys 222 – Supplemental Instruction
TUESDAY SESSION AS NORMAL – Q AND A
THURSDAY SESSION CANCELLED TO ACCOMMODATE EXAM REVIEW
Exam Overview



About 1/3 of the problems will stress conceptual
understanding

Don’t waste too much time on these

Think carefully!
Remaining 2/3 will be numerical problems to test ability
to apply these concepts

Know your formula sheet

Rule out wrong answers
25 + 2 Questions, 2 hours (4.4 minutes/problem)
Prepare yourself

Practice Problems!!


Practice tests (11 of them, with solutions)

It’s really easy to think you understand a concept, but then find out you can’t
solve a problem on it.

If you miss a problem, read the solution, then do it again later without the solution.

Old quizzes (make sure you understand mistakes)

Book problems (have answers in the back)

SI worksheets

Recitation problems
Concepts

Textbook

Online Summaries

Lecture Slides
Do you know all the following?
Fluid Statics
Density, pressure
Buoyancy, surface tension
Archimedes' Principal
Fluid dynamics
Bernoulli’s equation
Pascal’s law, continuity equation
Laminar flow
Electric Charge
Coulomb’s law
Charged objects’ behavior
Conductors, Insulators, Polarization
Electric Charge Interaction
Electric field, field lines
Dipoles, dipole moment
Flux
Integral Representation
Gaussian Representation
Applying Gaussian surfaces to objects
Electric Potential
(vs) Electric Potential Energy
Equipotential Diagrams
Calculating potential at various points
Movement of charge in the presence of a potential.
Relation to other types of energy
Capacitance
How various changes affect capacitance
What are their uses
Connections in circuits
Parallel vs series
Equivalent capacitance
Dielectric additions
Current
Relation to other concepts
Resistance
Connections, much like capacitors
Here we go!
LOTS OF TEST PROBLEMS WITH TIPS SPRINKLED IN
Useful tip

Store variables in your calculator

𝜖0

𝑘𝑒
Fluids!

Pressure = Force/Area (units depend on Area)

Archimedes principals

Buoyant force equal to weight of liquid displaced!

Pressure at a depth:

𝑃 = 𝑃0 + 𝜌𝑔𝑦

Don’t forget the Po!
1 2
𝑃 + 𝜌𝑔𝑦 + 𝜌𝑣 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
2

Classic problem: calculating velocity of water shooting out of a hole
in a container.

If pipe changes diameter, changes in velocity can be related to
changes in area with the continuity equation

In the case that the radius of a hole is very small, velocity simplifies

𝑣=

2𝑔𝑦
y is the depth at the hole
Electric Potential
Energy
Electric Force
Forces and energy: Do
depend on recipient and
emanating charge.
Emanating charge -- Q
Divide by q
Electric Field
Electric Potential
Difference
(voltage)
Field descriptions: Do not
depend on recipient
particle/charge.
Recipient charge -- q
Field lines!

Electric field lines go from + to -

Electric field lines end at negative charges.

Line density indicates field strength
Dipoles
(dipole moment)

𝒑 = |𝑄|𝒅

!! Notice: Dipole moment points from negative
to positive….opposite of the direction E points
Dipole Moment and Torque

𝝉 = 𝒑×𝑬
 Know
 This
right hand rule for cross products!
will help you eliminate wrong choices

Note that E is not the E produced by dipole. E is
external

Torque minimums and maximums
 Max

when p perpendicular to E
U = -p ⋅ E
Steps in solving GL Problems

Draw a picture.

Pick a good Gaussian surface. Symmetry!

Write expression of integral flux notation. (if E || A then, EA)

Write expression for Gauss’s Law involving enclosed charge.

Set the expressions equal and eliminate variables to solve.
Capacitance and Energy
1
𝐶𝑉 2
2
=
𝑄2
2𝐶
=
1
𝑄𝑉
2

𝑈=

Wait, why are there three equations?

If asked to calculate U, just use the one that has known variables

If asked what happens to U when you double, half, etc.

If the capacitors are stand alone, use Q^2 equation

If the capacitors are connected to constant voltage use V^2
equation
Combining components
Capacitors
Resistors
Addition
T = X1 + X2 +…
Inverse Addition
1/T = 1/X1 + 1/X2
+…
Inverse Addition
1/T = 1/X1 + 1/X2
+…
Addition
T = X1 + X2 +…
Parallel
Series
Hodgepodge
OF RELEVANT QUESTIONS