Electricity and Power Systems and Electronics, Lecture notes of Electrical Engineering

Download Electricity and Power Systems and Electronics and more Lecture notes Electrical Engineering in PDF only on Docsity! Electricity - Foundatio CM alt-it) Required Practical Investigating Resistance in a Wire Independent variable: length of the wire. Dependent variable: resistance. Control variables: type of metal, diameter of the wire. Conclusion: As the length of the wire increases, the resistance of the wire also increases. Investigating Series and Parallel Circuits with Resistors Independent variable: circuit type (series, parallel). Dependent variable: resistance. Control variables: number of resistors, type of power source. Conclusion: Adding resistors in series increases the total resistance of the circuit. In a parallel circuit, the more resistors you add, the smaller the resistance. Investigating I-V Relationships in Circuits (Using a filament bulb, ohmic conductor, diode.) Independent variable: potential difference/volts (V). Dependent variable: current (A). Control variable: number of components (e.g. 1 filament bulb, 1 resistor), type of power source. Set up the circuits as shown below and measure the current and the potential difference. IH IH H Draw graphs of the results once collected. Equations and Maths Equations Charge: Celt Potential difference. V=IR Energy transferred: E = Pt Energy transferred: E = QV Power: P=VI Power: P=PR Maths 1kwW = 1000W 0.5kW = 500W Charge Electric current is the flow of electric charge. It only flows when the circuit is complete. The charge is the current flowing past a point in a given time. Charge is measured in coulombs (C). Calculating Charge charge flow (C) = current (A) x time (s) Q=It potential difference = current x resistance V (V) =1(A) * R(Q) Resistance voltage (V) = current (A) * resistance () V=IR Graphs of I-V Characteristics for Components in a Circuit 1. Ohmic conductor: the current is directly proportional to the potential difference - it is a straight line (at a constant ~ temperature. This makes it harder for the current to flo\ temperature). 2. Filament lamp: as the current increases, so does the The graph becomes less steep. 3. Diode: current only flows in one direction. The resistance is very high in the other direction which means no current can flow. | it Current and Circuit Symbols Current: the flow of electrical charge. Potential difference (voltage): the push of electrical charge. Resistance: slows down the flow of electricity. cell | closed switch | —O—~O— fuse a A SS resistor a a ammeter Ay LDR “= b EF r (Vv) ED ae attery voltmeter ) u variable bulb —&e thermist varane ul ermistor open switch | —O-~~O— diode — Secondary Page 1 of 2 Dormston SCHOOL het rae