Electrical Circuits and Signals - Lecture Slides | ECE 110, Lab Reports of Electrical and Electronics Engineering

Download Electrical Circuits and Signals - Lecture Slides | ECE 110 and more Lab Reports Electrical and Electronics Engineering in PDF only on Docsity! ECE 110 M.-C. Brunet Electrical Circuits (Generalities), and Signals Handout 2 Symbol: V Unit: Volts THE VOLTAGE: to create an orderly movement of electrons we need: closed circuit (i.e. connected components) a voltage source (“power supply”) A Voltage Source: the battery (Volta 1792) - Th i- - + + + + + + + + - - - - - - - - ere s no accumulation of charge anywhere in the circuit (wire) - - - Chemical energy (E) forces movement of electrons There is a strong relationship between the current through and the voltage across any M.-C. BRUNET ECE 110 UIUC 2.1 Potential: V=E/Q component in a circuit. I = f(V) (see later topics) ECE 110 M.-C. Brunet Electrical Circuits (Generalities), and Signals Handout 2 A Circuit: TERMINOLOGY A component wire A Node: Any point on a wire (A) EL4 Set of components connected by wires B V Terminals: Wires connecting an element (nodes A and B are the two terminals for the component EL4) A = potential at A with respect to the ground Ground = any node in the circuit arbitrarily chosen as a reference node Voltage: voltage at Node A ( ) . [V(Ground)=0 is taken] Voltage difference of quantities= Symbol for Ground: (also: , ) M.-C. BRUNET ECE 110 UIUC 2.2 ECE 110 M.-C. Brunet Electrical Circuits (Generalities), and Signals Handout 2 All points connected by a wire have identical voltage Rule (*) A C Example 2: 1) Find and draw the direction of the positive current (assuming ideal circuits…) + - B D 20V battery resistor + ‐ V1 I in the circuit. 2) Find the voltage values asked 3) What happens if V = 0? VAB = V1= D M.-C. BRUNET ECE 110 UIUC 2.5 ECE 110 M.-C. Brunet Electrical Circuits (Generalities), and Signals Handout 2 Example 3: A + - B 20V battery Resistor 20 Ohms + ‐ V1 +-V2 Resistor 15 Ohms What can you say about V1, and V2? M.-C. BRUNET ECE 110 UIUC 2.6 ECE 110 M.-C. Brunet Electrical Circuits (Generalities), and Signals Handout 2 No Voltage no Current (across an element) A B + - If VAB = 0, then I AB = 0 No Current no Voltage!!! turning power off when modifying a circuit ! !!0V ≠+ - + 25v - battery no current (I=0) -- this is an open-circuit M.-C. BRUNET ECE 110 UIUC 2.7 ECE 110 M.-C. Brunet Electrical Circuits (Generalities), and Signals Handout 2 E1 I I ? Instruments +‐ +-v E2 V ? Am (I) t t curren amme er + 0 - 0 (V ) voltage voltmeter Vm (or multimeter) The instruments are assumed to be ideal (Am and Vm will provide the values for I, and , as if the instruments were not “there”) V E1 Am + ‐ E2 Vm M.-C. BRUNET ECE 110 UIUC 2.10 ECE 110 M.-C. Brunet Electrical Circuits (Generalities), and Signals Handout 2 Constant & time-varying signals DC signals: constant/time means Direct Current AC signals: Sine and Cosine (only!) means Alternative Current Other time-varying signals see CN#0 p.20 and Lab (function generator) Read about Instruments Multimeter (DC) Oscilloscope (non DC) and ideal/practical instruments M.-C. BRUNET ECE 110 UIUC 2.11 ECE 110 M.-C. Brunet Electrical Circuits (Generalities), and Signals Handout 2 AC signals examples Example 7 : V2(t) = 3 + 2sin(πt) Example 6 : V1(t) = 7sin (ωt) in radians V1(t) V2(t) ω=2πf t t Peak value = Ex. 7Ex. 6 7 Peak-to-Peak = Period T = Frequency f = 2π/ω ω/2π 14 Offset = M.-C. BRUNET ECE 110 UIUC 2.12 0 ECE 110 M.-C. Brunet Electrical Circuits (Generalities), and Signals Handout 2 I (A) Example 10: 2 7 10 I average = 21 3 4 65 t (ms) I2(A) 21 3 4 65 t (ms) I RMS = M.-C. BRUNET ECE 110 UIUC 2.15 ECE 110 M.-C. Brunet Electrical Circuits (Generalities), and Signals Handout 2 I (A) Example 11: 963 t (ms) 10 -5 I average = I2(A) 963 t (ms) I RMS = M.-C. BRUNET ECE 110 UIUC 2.16 ECE 110 M.-C. Brunet Electrical Circuits (Generalities), and Signals Handout 2 E2 i2 = 3A i0 1 E3E1v+-m v3 + - + -5v v2+ - Am imi1 i3 2 Give im, i3, v3, vm and i 0 (ideal Ammeter)(Voltmeter) 31 5 42 Name the pairs of elements in series, and in parallel7 . 3 1 im=3A, i3 = 0, v3 = 0 (= voltage across the ammeter). E3 is short-circuited (and im = i 2) 1 Name the pairs of elements in series, and in parallel. SOLUTIONS: M.-C. BRUNET ECE 110 UIUC 2.17 vm = 5v, io = 0 (voltmeter) (1,2) in series, (3,4) and (7,8) in parallel none3 2