2008 Ch 03_2

2008 Ch 03_2 - Making sense of Electrical Engineering 2nd...

• Notes
• 4

This preview shows pages 1–2. Sign up to view the full content.

Making sense of Electrical Engineering // 2 nd edition Chapter 3: Ohm’s Law // The Big Picture © 2008 Alexander Ganago The Big Picture: Ohm’s law, Sources, and Switches Ohm’s law is NOT among the fundamental laws of this Universe. It is merely a statement relating the current I through a circuit element to the voltage V across this element. According to Ohm’s law, they are proportional to each other: V = I R where the coefficient R is called resistance and is expected to be constant (independent of voltage or current). Ohm’s law, formulated by Georg Ohm in 1820s, has been experimentally confirmed for metals and some other materials, of which we build the circuit components called resistors, although their resistance depends on many parameters such as temperature. At the same time, there are many important exceptions to Ohm’s law, such as semiconductor devices, some of which we will discuss later. Accordingly, we use the term ohmic for circuit elements that obey Ohm’s law, and the term non-ohmic for those that lack the linear relationship between current and voltage. For an ohmic circuit element, we expect a linear dependence between voltage across and current through it (also called volt-amp characteristic or I-V curve) as sketched here along with the symbol used for resistors. Electrical engineers dearly love Ohm’s law, because it simplifies circuit equations to linear, algebraic instead of non-linear, differential, etc. It is indeed very convenient: given the voltage and resistance, you can easily find the current through a resistor and the power it absorbs (product of voltage and current, always positive for resistors).

This preview has intentionally blurred sections. Sign up to view the full version.

This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern