Reference no: EM133110140
Unit 15 Electrical Circuits and their Applications - Pearson BTEC Level 3 National Extended Diploma in Applied Science
Assessment - AB Circuits
Learning Aim 1: Understand electrical symbols, units, definitions, relationships and properties of circuit components for use in the construction of circuits.
Learning Aim 2: Construct series and parallel circuits for use in standard electrical applications and measure electrical values.
Assessment Brief:
Scenario
You are a trainee technician working for a company that specialises in producing specialist medical equipment such as electrocardiography, electromyography and electroencephalography machines.
As part of your induction, you have been asked to produce a report that demonstrates your knowledge of electrical concepts and shows that you are able to assemble various electrical circuits.
Task(s)
Using your notes and research, produce an ‘Electrical Circuits Information Report' containing the following sections:
Section 1 - Electrical symbols, units and definitions
State the symbols for the following cell components in a table:
• cell
• battery
• switch
• filament lamp
• fixed resistor
• thermistor
• light emitting diode (LED)
• light-dependent resistor (LDR)
• rheostat (variable resistor)
• capacitor
• voltmeter
• ammeter.
Produce a ‘Glossary of Terms' that defines and gives a brief explanation of each of the following:
• current (ampere)
• potential difference and EMF (volt)
• electrical charge (coulomb)
• resistance (ohm)
• conductance (siemen)
• electrical power (watt)
• capacitance (farad)
• current in terms of rate of flow of mobile charge carriers (electrons)
• electromotive force (EMF) as a measure of ratio of energy supplied per unit of charge
• conductance and resistance in relation to density of mobile charge carriers.
Section 2 - Electrical formulae and relationships
Draw diagrams of theoretical circuits and use the following formulae to accurately calculate a range of electrical quantities.
As part of your working, explain the following equations and how you have applied them:
• Energy supplied: E = VIt
• Kirchoff's first and second rules
• Ohm's Law: V = IR
• Power: P = IV, P = I2R
• Charge: Q = It
• Resistivity:
• Charge stored by a capacitor Q = CV
Section 3 - Electrical properties and uses of materials
Choose suitable examples of materials and their uses in order to provide an illustratedexplanation (i.e. with diagrams) of the following: conductivity, resistivity, insulators and conductors, ohmic and non-ohmic conductors and semi-conductors.
Section 4 - Experiment 1: Ohmic and non-ohmic behaviour
Accurately construct 2 circuits, each with one of the following components, with a switch and power source:
a commercial resistor;
a filament light bulb.
Connect an ammeter and voltmeter correctly in each circuit and record the voltage and current over a range of values for voltage. Use a table to present your readings.
Plot graphs of voltage against current for each of the 2 circuits. Interpret the graphs to evaluate which component obeys Ohm's Law and which does not.
Make comments about the accuracy of your practical readings and any suggested improvements you would make to your practical.
Section 5 - Experiment 2: Resistance in series and parallel circuits
Use two commercial resistors in a series, and then in a parallel, circuit. Draw the circuit diagrams. Compare measured values of total resistance to your predicted values of total resistance.
Use your calculations and comparisons to evaluate the operation of your circuits.
Section 6 - Experiment 3: Capacitors in series and parallel circuits
Accurately constructa simple circuit containing a capacitorsand a power pack.
Fully charge the capacitor using a known voltage. Take measurements of current against time whilst the capacitor is discharging, after your assessor has checked and confirmed that your circuit is safe.
Plot a graphs showing how current changes with time during discharge of the capacitor.
• Make a valid comment on your graph. What does the area under the graph represent?
Research the theory of capacitors in SERIES and IN PARALLEL and make predictions for the results you would expect if you had repeated your experiment with two identical capacitors in series and in parallel.
Section 7 - Experiment 4: Potential divider circuit
Voltage dividersare widely used in electrical circuits, where specific combinations of series resistors are used to "divide" a voltage into precise proportions.
Research how to build voltage divider circuits and demonstrate through experiment how to divide a 6.0V power output into approximately 1V, 2V and 3V using three resistors.
Show your calculations (Kirchoff's laws) to predict what voltage you will get from your resistors, and then measure the actual voltage. Compare your predicted and measured values.
Use your calculations and comparisons to evaluate the operation of your divider circuit. Your evaluation should consider the following:
• Reliability of your results over a given range
• Limitations of the investigation, and ways to improve future experimental work
Evidence of Requirements Checklist
An ‘Electrical Circuits information Report' that:
• explains the principle electrical terms, quantities and relationships
• evaluates the difference between ohmic and non-ohmic behaviour of components through practical investigation
• compares and evaluates predicted and measured resistances in series and parallel circuits
• compares the total capacitance in a series circuit to that in a parallel circuit
• investigates and evaluates the practical construction of a simple voltage divider circuit
• Include a Record of Observation signed by the lecturer.
Attachment:- Electrical Circuits and their Applications.rar