PHYS 154 Study Guide - Midterm Guide: Electric Field, Electric Charge, Electric Current
5/27/2018 Midterms
http://dunx1.irt.drexel.edu/~ferronfa/Midterm.html 2/3
1. Try the problems in the book, both multiple choice and long problems. One of the reasons we chose this book is for its ample supply of trial
problems. Especially note you can also use the "Check your understanding" sections.
2. Bearing in mind that not all the topics may apply, you can try problems from our own back exam file
3. Review the INVENTORY of concepts we have presented.
For Midterm 1:
•Everyday objects are charged by adding or removing electrons.
•Uncharged objects can be attracted if they become polarized
•The electrical force is HUGE.
•The electric field reveals the force IF a charge were present.
•The electric field goes from + to –
•Separated charges represent stored energy
•Electrons move UP a potential surface
•Capacitors use this in a practical way.
•Current only flows when there is a complete circuit
•Current flows because each charge has a path from high to low potential.
•Conventional current imagines positive charge moving: electrons move in the opposite direction
•Resistance comes from disorder, and generates heat in a circuit
For Midterm 2:
•A charge moving through a magnetic field experiences a force perpendicular to both.
•A wire in a magnetic field experiences a force if the field is perpendicular to the wire.
•A moving charge creates a magentic field.
•The right hand rule explains: (a) Force of a moving charge in a magnetic field,
(b) field around a wire (c) field around a coil. Know all 3.
•Electrons have spin, which makes them tiny magnets.
•Magnetic materials achieve magentism by aligning magnetic domains.
•Changing Flux generates an emf (Faraday’s Law)
•Induced current creates a magnetic field that opposes the original. (Lenz’ Law)
•Transformers can change AC voltage.
•Transformers have the same power out as power in.
•2 Postulates of Relativity
•Simutaneity fails for spatially separate events
•Moving clocks run slow
•Moving objects shorten
