Workbook - EEng (Part a)

8/14/2019 Workbook - EEng (Part a)

1/27

JAR 66 CATEGORY B1

MODULE 3A

ELECTRICALFUNDAMENTALS

WORKBOO

engineeringuk

K

Index

1 ATOMIC STRUCTURE ................................................................. 1-1

2 STATIC ELECTRICITY ................................................................. 2-1

3 ELECTRICAL TERMINOLOGY .................................................... 3-1

4 PRODUCTION OF ELECTRICITY ................................................ 4-1

5 CELLS & BATTERIES.................................................................. 5-1

6 OHMS LAW .................................................................................. 6-1

7 ELECTRICAL MEASURING INSTRUMENTS .............................. 7-1

8 RESISTANCE & RESISTORS ...................................................... 8-1

9 RESISTORS IN DC CIRCUITS ..................................................... 9-1

10 THE WHEATSTONE BRIDGE ...................................................... 10-1

11 ENERGY & POWER IN DC CIRCUITS ........................................ 11-1

12 CAPACITANCE & CAPACITORS ................................................ 12-1

13 CAPACITORS IN DC CIRCUITS .................................................. 13-1

14 MAGNETISM ................................................................................ 14-1

15 ELECTROMAGNETISM ............................................................... 15-1

16 INDUCTION & INDUCTORS ........................................................ 16-1

17 INDUCTORS IN DC CIRCUITS .................................................... 17-1

Issue 1 - 20 March 2001 Page 1-1


2/27


JAR 66 CATEGORY B1

MODULE 3A


WORKBOOK

engineeringuk

INTENTIONALLYBLANK


3/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

1 ATOMIC STRUCTURE

Answer the following questions in your own words.

Q1. What is the difference between an element, a compound and a mixture ?

Q2. Describe the structure of an atom. What is the significance of the chargeson the fundamental particles ?

Q3. What are ions and how are they formed ?

Q4. What is the significance of the number of electrons in the valance shell ?

Q5. Locate a table of elements that shows the distribution of electrons within theshells and determine how many electrons there are in the valence shell ofthe following material:

Aluminium

Silver

Copper

Gold

Germanium

Q6. Are there any elements that have more than 8 electrons in their outer shell ?(shell K,L,M,N,O,P or Q, not sub-shells)

Q7. Each shell is limited as to the number of electrons it can hold. Is there anyway of working out the maximum number of electrons that each shell canhold ?



4/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

2 STATIC ELECTRICITY

Q1. What is static electricity ?

Q2. Why must maintenance engineers consider static electricity when workingon aircraft:

i) electronic equipment

ii) structures

Q3. What is the Triboelectric series ?

Q4. What sort of potentials can be created by somebody walking across acarpet and does humidity have any effect on the value ?

Q5. As two charged bodies are moved apart, the force of attraction or repulsionbetween them decreases by the square of the distance (i.e. if the distancebetween them is increased from 1cm to 2 cm, the force decreases by afactor of 4. If the distance is increased to 3cm, the force decreases by afactor of 9), why ?



5/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

3 ELECTRICAL TERMINOLOGY

Q1. Define the following electrical terms in your own words:

i) Potential

ii) Potential difference

iii) Electromotive Force

iv) Voltage

v) Current

vi) Resistance

Q2. What is the difference between conventional current flow and electron flow ?

Q3. The following potential differences were measured in a circuit:

A is +4 volts with respect to (wrt) B

B is +3 volts wrt C

C is +2 volts wrt D

D is +1 volts wrt to ground

What is the potential difference of:

i) A wrt ground

ii) B wrt ground

iii) A wrt C

iv) B wrt D

Q4. The following potential differences were measured in a circuit:

E is at the same potential as ground and 25 volts wrt D

D is 15 volts wrt C

C is 10 volts wrt B

B is 30 volts wrt A

i) What are the potentials at B, C and D wrt ground.

ii) What is the potential difference of A wrt C.

iii) What is the potential difference of C wrt A.

iv) What is the potential difference of ground wrt B



6/27


JAR 66 CATEGORY B1

MODULE 3A


WORKBOOK

engineeringuk

Q5. The Following potentials were measured in a circuit:

E is at ground potential and A is +100 volts wrt ground

D is +50 volts wrt E

C is +15 volts wrt D

A is +20 volts wrt B

i) What are the potentials at B, C and D with respect to ground.

ii) What is the potential at C wrt B and D.

iii) What is the potential at B wrt E.

Q6. What is the difference between an emf and a potential difference ?

Q7. What factors affect resistance and how do they affect it ?

Q8. What is conductance and conductivity ?


7/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

4 PRODUCTION OF ELECTRICITY

Q1. Explain how a thermocouple produces electricity.

Q2. What happens when a force is applied to a piece of quartz crystal ?

Q3. Describe one aircraft related use of quartz crystals.

Q4. Investigate the construction and operation of a common primary cell andwrite a brief report on your findings.



8/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

5 CELLS & BATTERIES

Q1. What is the difference between primary and secondary cells?

Q2. A 25 A-h at the 10 hour rate battery can supply what maximum currentcontinuously and for how long ?

Q3. A 35 A-h at the 1 hour rate battery can supply what maximum current andfor how long ?

Q4. If a 40 A-h at the 10 hour battery was discharged at 8 Amps how long wouldyou expect it to be able to provide this current ?

Q5. When carrying out a capacity test on a 20 A-h battery, it only achieved 80%,what is the actual battery capacity ?

Q6. A battery was discharged at 10 Amps for 10 hours in order to test itscapacity. What was the batterys rating ?

Q7. If four 2 volt, 1 ampere-hour cells, each with an internal resistance of 2ohms are connected in series to form a battery, what is the battery voltage,capacity and internal resistance ?

Q8. How can a 4 volt, 6 A-h supply be obtained from six 2 volt, 2 A-h cells ?

Q9. Two 12 volt, lead acid, aircraft batteries are connected in parallel to give agreater capacity. Draw a circuit diagram depicting the individual cells ofthese two interconnected batteries.

Q10. What happens if a 4 volt battery is connected in parallel with a 2 voltbattery?

Q11. When 3 identical cells are connected in series across a filament, in whichorder do they discharge?

Q12. In your own words, describe the construction of a typical lead acid aircraftbattery.

Q13. In your own words, describe the construction of a typical Nickel Cadmiumbattery aircraft battery.

Q14. State some typical A-h ratings for lead acid and Ni-cad aircraft batteries.

Q15. What is thermal runaway and what might cause it occur ?



9/27


10/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

7 ELECTRICAL MEASURING INSTRUMENTS

Q1. What is the difference between an analog meter and a digital meter ?

Q2. What is the purpose of the mirror on an analog instrument ?

Q3. Explain why an ideal ammeter should have zero internal resistance.

Q4. Explain why an ideal voltmeter should have infinite internal resistance.

Q5. Find out what the internal resistance of one of the laboratory meters is onthe voltage and current ranges.

Q6. Should analog meters be laid down or stood up for an accurate reading ?

Q7. Describe in detail how a voltage measurement should be made.

Q8. Describe in detail how a current measurement should be made.

Q9. Describe in detail how a resistance measurement should be made.

Q10. Two 10Mresistors are connected in series across a 300 volt supply. If a

meter, having an internal resistance of 10Mon the appropriate range, is

used to measure the voltage drop across the two resistors, what valueswill be indicated on the meter.

Q11. Determine the internal resistance of the Electronic Workbench multi-meterwhen it is set to measure voltage. Explain how you obtained your answer.

Q12. Explain how a meter measures resistance.



11/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

8 RESISTANCE & RESISTORS

Q1. If the length of a conductor is doubled and its cross-sectional area halved,what affect will this have on its resistance ?

Q2. If the length of a conductor is doubled and its cross sectional area doubled,what affect will it have on its resistance ?

Q3. Do the following have positive or negative temperature co-efficient ofresistance:

i) Battery electrolyte

ii) Thermistors

iii) Copper wire

iv) Aluminium wire

v) Carbon

Q4. For what purpose would Eureka wire be used ?

Q5. Use the colour codes to work out the values of the following resistors:

i) Red Orange Yellow Gold

ii) Orange Orange Orange Red

iii) Violet Green Blue silver

iv) Green Green Black Gold

v) Brown Brown Black Brown

vi) Red Green Gold

vii) Brown Grey Gold

viii) Green Blue Silver

ix) Blue Yellow White Yellow Redx) Orange Brown Yellow Red Red

Q6. Assuming you want to use resistors with a 10% tolerance, what are theclosest preferred values for the following resistance values:

i) 13M Ohms

ii) 3.0K Ohms

iii) 4.9K Ohms

iv) 54K Ohms

v) 14.5K Ohms



12/27


JAR 66 CATEGORY B1

MODULE 3A


WORKBOOK

engineeringuk

Q7. For the preferred values selected in answer to Q6. Above. What are the

maximum and minimum values one could expect to find ?

Q8. What is the difference between a potentiometer and a rheostat ?

Q9. A resistor is connected across a potentiometer and the slider is increasedfrom minimum resistance to maximum (see diagram in notes p.8-7). Whataffect will this have on the voltage across the resistor and the currentflowing through it ?

Q10. A resistor is connected in series with a rheostat and the slider is moved fromminimum to maximum resistance (see diagram in note p.8-7). What affect

will this have on the voltage across the resistor and the current flowingthrough it ?

Q11. When current flows through a resistor, what affect is it likely to have on itsvalue of resistance ? Explain your answer.

Q12. Explain how can a thermistor be used to stabilise the current flowingthrough a coil of wire that tends to get hot when used.


13/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

9 RESISTORS IN DC CIRCUITS

Q1. Explain Kirchoffs second law.

Q2. Using Ohms law and Kirchoffs second law, derive the formula for the totalresistance of resistors connected in series.

Q3. A 12kresistor is connected in series with a 24kresistor across an 18volt supply. What is the circuit current and the voltage drop across eachresistor ?

Q4. Two 4.7kare connected in series across a 12 volt battery. What is thecircuit current and the voltage drop across each resistor ?

Q5. When a 1.2kresistor is connected in series with a 3.6kacross a powersupply, the current is 150mA. What are the voltage drops across theresistors ?

Q6. If three resistors of equal value are connected in series across a powersupply, what proportion of the supply voltage will be dropped across eachresistor.

Figure 1

Q7. Calculate the current flowing in the circuitof Figure 1.

Q8. Calculate the voltage drop across each ofthe resistors in Figure 1.

Q9. Calculate the voltage drops across each of theresistors in Figure 2.

Q10. Calculate the current flowing in the circuit of

Figure 2

Q11. Calculate the voltage at point B wrt point A inFigure 2.

Q12. Assuming a ground is placed at point C in Figure2, what will be the potential at point B wrt C ?

Q13. Assuming a ground is placed at point B in Figure2, what will be the potential at point B wrt C ? Figure 2



14/27


JAR 66 CATEGORY B1

MODULE 3A


WORKBOOK

engineeringuk

Q14. Assuming two resistors R1 and R2 are connected in series across VSupply,

complete the following table.

VSupply R1 R2 RTOT ISupply VR1 VR2

100V 1.2k 2.8k

12V 800 2400

24V 300mA 8V 16V

190mA 3.8V 5.7V

36V 3K6 7K2

60 120 3V

120V 40 40V

1000V 12M 56M

300 13k 1.6A

24V 300 24mA

100V 1700 34V

400 1000 5.2V

Q15. The off-load voltage of a power supply is 100 volts. When the supply is

connected to a 200resistor the terminal voltage falls to 90 volts. Calculatethe internal resistance of the power supply.

Q16. The off-load voltage of a power supply unit is 28 volts, the on-load voltage is

26 volts. If the load is 600, calculate the internal resistance of the powersupply unit.

Q17. The internal resistance of a 30 volt power supply is 60, calculate the

terminal voltage when it is connected to a 240load.


15/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

10 THE WHEATSTONE BRIDGE

Refer to Figure 1 to answer the following questions

Q1. If R1=R2=R3=R4 and E=24 volts:

A. Calculate the current flowing throughR1 and R2.

B. Calculate the potential differencebetween points A and B.

C. If E was decreased to 20 volts, whataffect would it have on the potential

difference between points A and B ?

Figure 1Q2. If R1= 200, R2= 600, R3= 1kand E=16 volts:

A. What value must R4be to balance the bridge.

B. What will be the current flowing in R2.

C. What will be the potential at A.

Q3. If R1= 2k2, R2= 32k, R4= 80kand E=21 volts:

A. What value of R3will balance the bridge.

B. If R3has a value of 4k4, what will be the potential difference betweenpoints A and B.

C. If R3has a value of 1k1, what will be the potential difference betweenpoints A and B.

Q4. On connecting the Wheatstone Bridge circuit shown, the meter indicated fullscale deflection. Discuss possible fault conditions that would exhibit thesesymptoms.

Q5. On connecting the Wheatstone Bridge circuit shown, the meter needleabutted against the zero end-stop. Discuss possible fault conditions thatwould exhibit these symptoms.



16/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

11 ENERGY & POWER IN DC CIRCUITS

Q1. How much work is done if 3 coulombs of charge is moved through apotential of 20 volts. (60 Joules)

Q2. How much work is done when 10 amps flows through a potential of 6 voltsfor 2 minutes. (7200 Joules)

Q3. How much energy is used when 3 amps flows through a potential of 5 voltsfor 10 minutes. (9 kJoules)

Q4. The voltage across a 3k2resistor in an electrical circuit is 6 volts. Howmuch energy is used in pushing the current through this resistor for 1

minute. (0675 Joules)Q5. 6 amps flows through a 12 volt filament in a circuit. Calculate the:

A. work done by the circuit if the filament is on for 2 hours.

B. energy used by the filament in 2 hours.

C. rate at which work is being done by the filament.

Q6. Assuming the circuit comprises a single resistor connected across a voltagesource, complete the following table.

Voltage

(v)

Resistance

()Current

(I)

Power

(W)

Work Done in

10 mins (J)

10 Volts 600

24 Volts 1200 Watts

2 Amps 400 Joules

24 Volts 320 Joules

200 40mAmps

28 Volts 300 Watts

120 Volts 3k6

Q7. If a 2.5kW kettle is left switched on for 10 minutes, how much energy isused in kWhs.

Q8. If 1kWh costs 7 pence, how much will it cost to keep a 100 Watt light on for6 hours per day for 7 days.

Q9. What is the maximum voltage and current that can be applied to a 300resistor with a 20 Watt power rating.

Q10. What is the maximum voltage and current that can be applied to a 4k7resistor with a 30 Watt power rating.



17/27


JAR 66 CATEGORY B1

MODULE 3A


WORKBOOK

engineeringuk

Q11. A 28 volt power supply with an internal resistance of 100is connected to a

100load. Calculate the:A. circuit current.

B. power dissipated in the load.

C. power supply terminal voltage when connected to the load.

Q12. A light bulb, rated at 100 Watts, is connected across a 240 volt supply.Calculate the circuit current and the resistance of the filament when the lightis on.

Q13. A light bulb, rated at 100 Watts is connected across a 28 volt supply.Calculate the circuit current and the resistance of the filament when the light

is on.Q14. How much power will be dissipated by a 3k6resistor with 6 amps of

current flowing in it.


18/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

12 CAPACITANCE & CAPACITORS

Q1. A simple parallel plate capacitor has plates with an area of 10cm2, adistance of 001mm between the plates and a dielectric material betweenthe plates with a relative permittivity of 40:

A. Calculate the capacitance of the capacitor.

B. What would have to be done to the distance between the plates todouble the capacitance of the capacitor.

C. What would have to be done to the cross sectional area of the plates tohalf the capacitance of the capacitor.

D. If the dielectric is replaced by a material with twice the relative

permittivity, what affect will it have on the capacitance of the capacitor.

Q2. Calculate the capacitance of a simple parallel plate capacitor which hasplates of cross sectional area of 100cm2, a distance of 0015mm betweenthe plates and a dielectric material between the plates with an absolutepermittivity of 8x10-9Fm-9.

Q3. Calculate the capacitance of a simple parallel plate capacitor which hasplates of cross sectional area of 200cm2, a distance of 0025mm betweenthe plates and a dielectric material between the plates with a relativepermittivity of 300.

Q4. A simple parallel plate capacitor has plates with an area of 150cm

2

, adistance of 002mm between the plates and a dielectric material betweenthe plates with a relative permittivity of 350. Calculate the:

A. Capacitance of the capacitor.

B. Charge on the capacitor if it is fully charged on a 28 volt supply.

C. Energy stored in the capacitor when it is fully charged.

Q5. A multi-plate capacitor has 9 plates each with a cross sectional area of4cm2. The distance between the plates is 015mm and the dielectricmaterial between the plates has a relative permittivity of 50. Calculate the:

A. Capacitance of the capacitor. (944nF)


C. Energy stored in the capacitor when it is fully charged to 28 volts.

Q6. A multi-plate capacitor has 3 plates each with a cross sectional area of500cm2. The distance between the plates is 10mm and the dielectricmaterial between the plates has a relative permittivity of 4. Calculate the:

A. Capacitance of the capacitor. (354nF)


C. Energy stored in the capacitor when it is fully charged to 28 volts.



19/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

13 CAPACITORS IN DC CIRCUITS

Q1. A simple parallel plate capacitor has plates with an area of 12cm2, adistance of 001mm between the plates and a dielectric material betweenthe plates with a relative permittivity of 40:

A. Calculate the capacitance of the capacitor.

B. Calculate the electrical energy stored in the capacitor if it is connectedacross a 28 volt supply.

C. Calculate the charge on the capacitor if the potential is across it isincreased to 100 volts.

Q2. Complete the following table.

Capacitor 1 Capacitor 2 Capacitor 3 ConnectionTotal

Capacitance

100F 200F none Series

200F 100F none Parallel

100F 300F 200F Series

470F 470F none 235F

47F 100F none 32F

30F 470F 100F Parallel



30F 100F Parallel 177F

200F 400F Series 100F

Q3. A 400F capacitor is connected in series with a 200F capacitor across a

120 volts supply. Assuming the capacitors are fully charged, calculate the:A. Voltage across each capacitor.

B. Energy stored in each capacitor.

Q4. A 47F capacitor is connected in series with a 100F capacitor across a 28volts supply. Assuming the capacitors are fully charged, calculate the:

A. Charge on each capacitor

B. Voltage across each capacitor.

C. Energy stored in each capacitor.

D. Total charge on both capacitors.



20/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

Q5. C1=100F, C2=200F and VSUPPLY= 60 volts. Assuming the capacitors are

connected in series across the power supply, calculate the voltage dropacross each capacitor (C1 40 volts, C2 20 volts)

Q6. C1=100F, C2=200F, C3=400and VSUPPLY= 120 volts. Assuming thecapacitors are connected in series across the power supply, calculate the:

A. Total capacitance.

B. Voltage drop across each capacitor.(V1 - 6857 volts, V2 3428 volts, V3 - 1714 volts)

C. Charge on each capacitor.

D. Energy stored in each capacitor.

Q7. C1=120F, C2=170F, C3=90F and VSUPPLY= 100 volts. Assuming thecapacitors are connected in series across the power supply, calculate the:

A. Total capacitance.

B. Voltage drop across each capacitor.(V1 - 329 volts, V2 2323 volts, V3 - 4387 volts)



Q8. C1=10F, C2=100F, C3=170F and VSUPPLY= 100 volts. Assuming thecapacitors are connected in series across the power supply, calculate the:

A. Total capacitance.B. Voltage drop across each capacitor.

(V1 - 8629 volts, V2 863 volts, V3 - 508 volts)





21/27


22/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

14 MAGNETISM

Q1. Describe the domain theory of magnetism.

Q2. Explain how lines of flux can be demonstrated to a group of students.

Q3. Describe the Earths magnetic field and explain the terms dip and variation.

Q4. Describe one use for a hard iron material and one use for a soft ironmaterial. Explain how the materials magnetic properties are exploited.

Q5. Explain how components can be shielded from magnetic fields.

Q6. Explain why might it be necessary to shield components from magneticfields.



23/27


24/27


JAR 66 CATEGORY B1

MODULE 3A


WORKBOOK

engineeringuk

Q8. An iron ring of mean circumference 50cm has an airgap of 01cm and is

wound with a coil of 120 turns, If the relative permeability for the iron is 350when a current of 25 amps flows in the coil, calculate the flux density.(254mT)

Q9. A steel ring has a mean diameter of 20cm and a cross-sectional area of

1.5cm2broken by a parallel sided airgap of length 05cm. Taking r= 500,calculate the current necessary in 3000 turns of wire wound on the ring toproduce a flux density of 05 Tesla in the airgap and the total flux in the steelring. ( )

Q10. A steel ring having a mean diameter of 35cm and a cross-sectional area of24cm2is broken by a parallel sided airgap of length 12cm. Short pole

pieces of negligible reluctance extend the effective cross-sectional area ofthe airgap to 12cm2. Taking r= 700 and neglecting leakage, determine thecurrent necessary in 300 turns of wire wound on the ring to produce a fluxdensity in the airgap of 025 Tesla. (13.17 Amps)

Q11. A steel ring having a mean diameter of 25cm and a cross-sectional area of12cm2is broken by a parallel sided airgap of length 16cm. Short polepieces of negligible reluctance extend the effective cross-sectional area of

the airgap to 10cm2. Taking r= 600 and neglecting leakage, determine thecurrent necessary in 3000 turns of wire wound on the ring to produce a fluxdensity in the airgap of 05 Tesla. ( Amps)


25/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

16 INDUCTION & INDUCTORS

Q1. The current flowing in a 200 mH inductor is changing at a rate of 10 ampsper second, calculate the back emf in the coil.

Q2. Two inductors of 100mH each are connected in series aiding. What is thetotal inductance if the coupling factor is:

A. Zero

B. 0707

C. one

Q2. A 100mH inductor is connected in series aiding with a 300mH inductor.

What is the total inductance if the coupling factor is:A. 025

B. 05

C. 095

Q3. If two similar inductors (coils) are lying at 90 degrees to each other, whatvalue of coupling factor would you expect ?

Q4. A 100mH inductor is connected in parallel with a 60mH inductor andpositioned so that no mutual coupling exists between them. Calculate thetotal inductance.

Q5. Two 200mH inductors are connected in parallel and positioned so that nomutual coupling exists between them. Calculate the total inductance.



26/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOO

engineeringuk

K

17 INDUCTORS IN DC CIRCUITS

Q1. A 100mH inductor is connected in series with a 500resistor across a 20volt power supply.

D. Calculate the circuit time constant.

E. Calculate how long will it take for the circuit current to reach itsmaximum value.

F. Calculate the voltage across the resistor after 1 time constant.

G. Calculate the maximum value to which the current will rise.

H. Show that at the instant the switch is closed, the back-emf produced bythe inductor is equal to the supply voltage.

I. Calculate the energy stored in the magnetic field when the current hasreached its maximum value.

Q2. With reference to Figure 1. A60mH inductor is connected in

series with a 900resistor,across a 12 volt power supply.

A. Sketch a graph to show thecircuit current with respect totime when the switched ismoved to position A.

Figure 2

B. Sketch a graph to show the voltage across the inductor with respect totime when the switched is moved to position A.

C. Sketch a graph to show the voltage across the inductor when the switchis moved directly from position A to position B.

D. Sketch a graph to show the circuit current when the switch is moveddirectly from position A to position B.

(although only a sketches are required, graphs should be accurate at pointswhere calculations can be made)

Q3. A 10mH inductor is connected in series with a 36kresistor across a 14 voltpower supply, calculate the:

A. circuit time constant.

B. maximum circuit current.

C. circuit current after 1 time constant.

D. voltage across the inductor after 1 time constant.

E. energy stored in the magnetic field when the current has reached its

maximum value.



27/27

JAR 66 CATEGORY B1

MODULE 3A


WORKBOOK

engineeringuk

Q4. A 15mH inductor is connected in series with a 470resistor across a 12

volt power supply, calculate the:A. circuit time constant.

B. circuit current after 1 time constant.

C. voltage across the resistor after 1 time constant.

D. energy stored in the magnetic field when the current has reached itsmaximum value.

Q5. When an inductor of unknown value was connected across a 12 volt powersupply, the current settled at 300mA after 200mS. Calculate the:

A. resistance of the inductor.

B. circuit time constant.C. voltage across the inductor after 1 time constant.

Q6. If an ideal capacitor was fully charged on a power supply and thenconnected across an ideal inductor. Explain what would happen. (an idealcapacitor has no inductance or resistance and an ideal inductor has nocapacitance or resistance)

Q7. A real capacitor is fully charged on a power supply and then connectedacross an actual inductor. Explain what happens.

Q8. Explain how a coil, connected into 24 volt d.c. circuit, could produce a back

emf of 2000 volts.

Documents

Workbook - EEng (Part a)