1) In a DC motor the stator magnetic field due to armature reaction moves
a) In the sane direction of rotation
b) In the opposite direction to rotation
c) In alignment with GNA
2) A 20 Pico farad capacitor with a 1MW resistor takes how long to charge
a) 20m seconds
b) 1 second
c) 10 seconds
3) Heat exposed to a material will
a) Make all materials harder to magnetise
b) Make all materials easier to magnetise
c) Have no effect on magnetism
4) A transformer has 2000v, 500 turns on the primary and 50 turns on the secondary. What would be the line voltage if the transformer were Delta/Star connected?
a) 200v
b) 346v
c) 450v
5) A transformer to supply a 24v load with a 5:1 turns ratio will have what primary supply?
a) 120v DC
b) 48v AC
c) 120v AC
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6) A transformer has 750 primary turns and 4500 secondary, its turns ratio is
a) 6:1
b) 1:6
c) 1/6
7) A band stop filter will
a) Pass all frequencies either side of the band
b) Stop all frequencies either side of the band
c) Stop all frequencies
8) What is this circuit?
a) High Pass Filter
b) Low Pass Filter
c) Band Stop
9) In this circuit, Rx is equal to
a) R3 x R2 ¸ R4
b) R3 x R4 ¸ R2
c) R2 x R3 ¸ R4
10) A parallel circuit with any number of 2 terminal connections
a) Has the same current throughout
b) The sum of the individual voltage drops is equal to the emf
c) The resistance is dependent on current
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11) 2 coils, which are turned from being in parallel to 90° but in close proximity, will have its mutual inductance
a) Decreased
b) Remain the same
c) Increase
12) If armature speed is doubled and field strength halved, field strength will
a) Halve
b) Remain the same
c) Double
13) In a circuit with voltage and current which is purely resistive will have its voltage with respect to current
a) In phase
b) 90° Leading
c) 90° Lagging
14) Average value of voltage is equal to
a) 1.1
b) 0.627 x Peak
c) 0.707 x Peak
15) What wave shape is used to control sweep in a CRT?
a) Sine wave
b) Square wave
c) Saw tooth
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16) In a 3 phase AC motor, if one phase goes open circuit the motor with a light constant load will
a) Stop
b) Run slowly
c) Run normally
17) Line voltage in a Wye wound transformer is
a) Ö3 ¸ Phase voltage
b) Same as phase voltage
c) Ö3 x Phase voltage
18) To calculate generator output you need to know
a) Armature speed and number of series conductors
b) Field strength and number of armature parallel conductors
c) Series field strength and armature speed
19) What charge does an electron have?
a) Positive
b) No charge
c) Negative
20) An atom, which has gained an electron, will become
a) A negative ion
b) A positive ion
c) A neutral atom
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21) An atom, which has few electrons in its valency (less than 4), will have
a) Low resistance
b) High resistance
c) No resistance
22) A 40AH battery will supply 200mA for
a) 250 hrs
b) 40 hrs
c) 200 hrs
23) A 24v, 10 A circuit wit 0.5W resistance will have what power
a) 50W
b) 100W
c) 150W
24) An electrolytic capacitor is used where
a) There is a polarised supply
b) Light loads are used
c) Low frequencies are used
25) A combined starter generator has a
a) Low resistance shunt field and high resistance series field
b) Low resistance series field and high resistance shunt field
c) High resistance shunt field and high resistance series field
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26) To find the direction of current in a coil you would use
a) Flemmings R/H rule
b) Flemmings L/H rule
c) Corkscrew rule
27) In a transformer, if the rate of change of current is decreased, mutual inductance will
a) Remain the same
b) Increase
c) Decrease
28) If the brake coil in an actuator goes open circuit the actuator will
a) Over ride its mechanical stops
b) Continue to run
c) Stop
29) The speed of a generator with 400Hz supply and 4 poles is
a) 6000 RPM
b) 10000 RPM
c) 12000 RPM
30) An inductance/resistance starter motor is
a) Better than a capacitive
b) More efficient that a capacitive
c) For light loads only
31) The voltage at point C would be equal to
a) 10 V
b) 7V
c) 28V
32) With an output of 200V in a short shunt configuration, the voltage at the series field resistor would be
a) 6 V
b) 10V
c) 450V
33) At point B a voltage in a wire would be
a) Maximum
b) Minimum
c) Zero
34) An ideal 4:1 step down transformer draws 115V and 1A, the output would be
a) 28.5V at 1 A
b) 28.5V at 4 A
c) 460V at 4 A
35) The voltage induced in the stator of an AC generator is produced by
a) A fixed magnetic field
b) A rotating magnetic field
c) An alternating field
36) A low frequency supply
a) May damage inductive circuits
b) Will make the circuit operate faster due to loss of impedance
c) No effect on inductive components
37) A zinc carbon battery life depends on
a) Amount of zinc
b) Purity of carbon
c) Amount of electrolyte paste
38) A batteries terminal voltage at open circuit, with low internal resistance will be
a) Same as the emf
b) Smaller than the emf
c) Greater than the emf
39) When checking the specific gravity of electrolyte in a lead acid battery
a) Check all the cells as they may vary
b) Check the two front cells as they are the terminal cells
c) Check any cell as the will all be the same
40) When a Nickel Cadmium battery is to be stored it should be done
a) Fully charged
b) Fully discharged
c) Totally dry
41) A circuit with a 14.14 peak voltage and a 10W resistance will have a power output of
a) 141.4 W
b) 1.414 W
c) 10 W
42) The power of a piece of equipment with 24V supply with 0.5W resistance and 80A has how much power dissipated?
a) 320 KW
b) 3200 KW
c) 3.2 KW
43) What must you do to make a 3m farad circuit into a 2m farad circuit?
a) Place 1m farad in series
b) Place 3m farads in parallel
c) Place 6m farads in series
44) What does this symbol represent?
a) Light dependent resistor
b) Laser dependent resistor
c) Laser dependent rectifier
45) A parallel circuit at resonance has its impedance at a
a) Maximum
b) Minimum
c) Zero
46) In a capacitive circuit, if frequency is increased
a) Current increases
b) Impedance increases
c) Current decreases
47) If the energy supplied to a circuit for 4hrs 15 mins at 800 j/sec what would be the energy consumed?
a) 3.4 KW Hrs
b) 3400 KW Hrs
c) 340 KW Hrs
48) When switching off the supply, the back emf in a collapsing field in an inductor
a) Never exceeds forward emf
b) Can be multiple times bigger than forward emf
c) Is equal to forward emf
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