electric current in a conductor is the flow of .....
- protons
- neutrons
- electrons
- positrons
EMF can be derived from which one of the following sources of energy?
- thermal, magnetic, chemical
- wind, chemical, thermal
- nuclear, atomic, magnetic
- solar, chemical, magnetic
an increase in current in a conductor will cause the temperature in the conductor to...
- increase
- decrease
- remain unchanged
- vary
identify the (SI) symbol for Inductive Reactance
- Xc
- XL
- Z
- ohms
identify the (SI) symbol for the unit of measure of capacitance
- C
- F
- Q
- V
identify the (SI) symbol for Inductance
- L
- Z
- Cos0
- I
identify the (SI) symbol for reactance
- Xc
- XL
- Z
- X
state the correct units of measure (in order) for; P.D, Impedance and current
- hertz, ohms and amperes
- volts, watts and amperes
- volts, ohms and amperes
- hertz, henrys and amperes
if three resistances of 12 ohms, 28 ohms and 15 ohms are connected in SERIES, calculate the total resistance.
- 36 ohms
- 55 ohms
- 45 ohms
- 56 ohms
if three resistances of 12 ohms, 28 ohms and 15 ohms are connected in PARALLEL, calculate the total resistance.
- 3.68 ohms
- 5.38 ohms
- 13.88 ohms
- 12.82 ohms
if a circuit has a total resistance of 20 ohms and is supplied at 50v, calculate the power in the circuit
- 125w
- 1000w
- 2.5w
- 70w
in order to make a measurement of current in a DC circuit, the ammeter must be connected....
- in series with the load
- in parallel with the load
- across the AC supply
- between the + and - of the supply
in order to make a measurement of voltage in a DC circuit, the voltmeter must be connected....
- in series with the load
- in parallel with the load
- across the AC supply
- at the end of the circuit
which method below would increase the strength of magnetic flux in an electromagnet?
- an increase in current
- a decrease in current
- less turns on the coil
- reversing the current flow
in a balanced STAR system drawing 10A on each phase, the current carried by the neatral would be...
- 30A
- 10A
- 0A
- 3.33A
in a STAR system drawing 20A on two phases and 15A on the remaining phase, the current carried by the neutral would be...
- 35A
- 10A
- 5A
- 0A
a circuit with high inductance can have its power factor improved by the addition of..
- further inductors connected across the load
- capacitors connected across the load
- resistors connected in parallel with the load
- resistors connected in series with the load
identify the 'standard' numeric value use for gravity (in metres per second-squared)
- 9.81
- 5.81
- 19.81
- 8.91
a crowbar is an example of a ....
- class 1 lever
- class 2 level
- class 3 lever
- class 4 lever
a transformer has an input voltage and current of 100v and 10A. If the output current is 1A, calculate the output voltage
- 1000v
- 50v
- 500v
- 10v
what is meant by the letter V in the abbreviation VFD, in relation to motor control
- voltage
- variable
- voltaic
- varied
electrical connections made to the armature of a DC motor is achieved by the use of
- brushes and slip-rings
- brushes and commutator
- wiring the supply directly
- magnetism