110 lines
2.9 KiB
Markdown
110 lines
2.9 KiB
Markdown
## **Main topics:** Introduction, Basic concepts, Ohm’s law
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- pass the circuit labs
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- mandatory!
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- 2 partial exams
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- trial exam week 4
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- 6 SGH's --> only best 5 count
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- bonus points --> dewit
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- check [Brightspace](https://brightspace.tudelft.nl)
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-----
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# Content
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Syllabus on [Brightspace](https://brightspace.tudelft.nl)
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- Dc circuits
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- Basis
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- electrical elements
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- circuit analysis methods
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- Dynamic circuits
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- end of q1 with Time-domain solutions
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-----
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# Actual lecture
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#OhmsLaw
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## The basis
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- Volta --> sustained electrical stimulus "Volta Pile"
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- move cells ("More Volts") --> more "energetic" a stimulus
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- nr of volts = voltage
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- **one always needs 2 points for tapping the energy**
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- Voltage -> 2 access points
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- An electric current deflects a magnetic needle
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- galvanometer --> precise method for measuring electric currents
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- measures current and uses fancy math to measure volts
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- two basic, easily measurable quantities
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- voltage + current
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- Pairs of access points
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- at which the supplied energy
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- between which the current
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**Both can be unambiguousy measured** (predicted)
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= ports
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Circuit analysis = the analysis of the relations between voltages and currents at given ports
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We study circuits
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- made from electrical elements (lumped elements , idealized)
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- connecting wires (ideally 0 v over the wires)
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### Si system
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current -> Ampere
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Charge -> s\*A -> Coulomb (C)
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electrical potential -> volt
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Charge = an electrical property of sub-atomic constituents measured in Coulomb (C)
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charge of electron = e = -1.6 \* 10^-19 C
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Electric current: a measure of the temporal variation of the electric charge, measured in A(mpere)
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$$
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i = \frac{dq}{dt} \newline
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$$
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DC = a current that remains constant with time
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AC = current that varies sinusoidally with time
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A positive value for the current indicates a flow in the direction of the arrow (reference direction)
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a negative value -- \\ -- in the opposite direction of the arrow
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the potential difference between two points is denoted as voltage
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the potential is the electrical potential energy per unit charge
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$$
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V_ab = \frac{w}{q}
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$$
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Voltage --> across
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Current --> through
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power = energy/time
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instantatneous power = p = dw/d = dw/dq \* dq/dt = v\*i
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energy -> power (iintegration)
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$$
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w(t) = \int
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$$
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if voltage and current are both positive --> the positive charges move from a higher potential to a lower potential (in the direction of the current) (from + to -)
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The component absorbs power --> passive component
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\
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### Resistance and ohms law
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- ratio v(t)/i(t) at the same time instant t
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- = elements ability to resist the flow of electric current
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- wire like conductors
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$$ R = \rho \cdot \frac{l}{A} \newline $$
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$$ \rho = resitivity $$
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$$ l = length\ of\ wire $$
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A = cross-sectional area
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conductance = reciprocal or resistance
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\[G\] = S(iemens)
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$$ G = \frac{1}{R} = \frac{i}{v} $$
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most materials have non-linear resistance
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