class: center, middle # EE-281 ELECTRIC CIRCUITS ## Ozan Keysan [ozan.keysan.me](http://ozan.keysan.me) Office: C-113 <span class="meta">•</span> Tel: 210 7586 --- # Resistance & Resistivity ### $$R = \rho \frac{L}{A} \quad \Omega $$ ### L: length, A: Area, \\(\rho\\): Resistivity ( unit: \\(\Omega . m \\) ) -- ## What is the best conductor? -- - **Aluminium:** \\(2.82\; 10^{-8} \; \Omega.m \\) -- - **Copper:** \\(1.68 \; 10^{-8} \; \Omega.m \\) -- - **Silver:** \\(1.59 \; 10^{-8} \; \Omega.m \\) -- - **Gold:** \\(2.44 \; 10^{-8} \; \Omega.m \\) --- ## Why some connectors are gold plated?  ### Gold Plated High Speed HDMI cable [199 TL](http://www.hepsiburada.com/profigold-oxypure-1-metre-hdmi-kablo-p-EVERDGOXYV1201) --- # Ohm's Law ### $$Voltage = Current \times Resistance $$ -- ### $$ V = I R $$ <img src="http://www.sengpielaudio.com/ohms-law-illustrated.gif" alt="Drawing" style="width: 300px;"/> --- # Terms in Circuit Diagrams ## Node: -- Point of connection between elements. -- ## Branch -- : Connection between two nodes. -- ## Loop: -- Closed loops in circuit diagram. -- ## ! Number of Branches = # of Loops + # of Nodes - 1 --- # Kirchhoff's Current Law -- ### Algebraic sum of currents entering a closed a node (or a loop) is zero. ### $$\sum I_n =0$$ -- <img src="http://www.electronics-tutorials.ws/dccircuits/dcp6.gif" alt="Drawing" style="width: 600px;"/> --- # Kirchhoff's Voltage Law -- ### Algebraic sum of all voltages around a closed path (or loop) is zero. ### $$\sum V_n =0$$ -- <img src="https://upload.wikimedia.org/wikipedia/commons/thumb/4/40/Kirchhoff_voltage_law.svg/600px-Kirchhoff_voltage_law.svg.png" alt="Drawing" style="width: 250px;"/> ### If you meet with negative terminal of an element first, write that voltage as negative to the equation. --- # Series Resistors <img src="http://upload.wikimedia.org/wikipedia/commons/thumb/5/5d/Resistors_in_Series.svg/600px-Resistors_in_Series.svg.png" alt="Drawing" style="width: 600px;"/> -- ## $$R_{tot}=R_1+R_2+R_3 ... R_n$$ --- # Parallel Resistors <img src="http://upload.wikimedia.org/wikipedia/commons/thumb/6/64/Resistors_in_Parallel.svg/600px-Resistors_in_Parallel.svg.png" alt="Drawing" style="width: 600px;"/> -- ## $$ \frac{1}{R_{tot}} = \frac{1}{R_1} + \frac{1}{R_2} ... + \frac{1}{R_n} $$ --- # Parallel Resistors ## Two Resistors ## $$ R_{tot} = \frac{R_1 \times R_2}{R_1 + R_2} $$ --- # Examples --- # Any questions? ## You can download this presentation from: [keysan.me/ee281](http://keysan.me/ee281)