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Physics 216L lab final study guide

It is important to study for the lab final! As a reminder, it counts as 20% of your overall lab course grade. It is closed books and notes. You will have up to 2 hours to complete it. You should bring a calculator.

The lab final is comprehensive, covering material from all 11 labs. There will be about 30 – 35 questions or about 3 questions per lab. It is primarily multiple-choice with some short answer. It will be conceptual in nature, similar to the in-lab material and homework assignments. Study the homework, if you can do the homework problems and are comfortable with the lab work, you will be in good shape for the final!

It is important that you know the basic formulas and how to apply them. These would include, but are not limited to:

• Coulomb’s Law, F=kqq/r^2

• Electric Field, E=F/q. The electric field points in the direction a positive charge will go.

• Electric potential difference, dV = -W/q . The electric potential difference, dV, is the work done by the field on the charge q, as it travels from point a to point b.

• Know what an equipotential line or surface is; all points along this line or surface are at the same electric potential. The electric field E, is always perpendicular to an equipotential surface. Thus, if the net work done on the particle by the field is zero, the particle is traveling along an equipotential surface.

• Know Ohm’s Law, V = IR and how to analyze simple circuits. For resistors in series the equivalent resistance is Req = R1+R2+…, for resistors in parallel the equivalent resistance is 1/R = 1/r + 1/r
  
• Know Kirkoff’s Rules, the junction rule states the sum of the currents meeting at a junction in a circuit must be zero and the loop rule states the sum of all potential differences around a closed loop in a circuit must be zero.
  
• Know the basic principles about magnets and the direction of a magnetic field; that a current carrying wire will produce a magnetic field and how to determine that direction.
  
• Know the right-hand rules.
  
• Lorentz Force, F = qv x b and F = il x b.
  
• You will be given the more complicated formulas, such as the equation for the charge-to-mass ratio (e/m) of an electron.
  
• Know how the different experimental parameters such as B, V, r, and e/m are related and how changing one will affect another and that the ratio, e/m, is a constant!
  
• Lenz’ Law, if an induced current flows, it will be in such a direction that the magnetic field it produces tends to counteract the change in flux that induced the emf.
  
• Faraday’s Law : emf, epsilon = - dflux/dt, or the average emf induced in a loop is epsilon = - dflux/dt, where dflux is the change in flux through one loop and dt is the time interval during which the change occurs. Flux, = BA cos. The negative sign in Faraday’s Law is given by Lenz’ Law.
  
• Know how to ray trace; to find an image of an object produced from a plane mirror, curved mirror and convex lens and what type of image is formed – real or virtual.
  
• Know how light is refracted when it travels from one media into another – when light travels from a media with a lower index of refraction to one with a higher index of refraction it bends toward the normal to the surface and vice-versa (traveling from higher to lower index it bends away from the normal).