112 EXAM 1 Flashcards
(39 cards)
If an electron is gained or lost from an atom, that atom becomes
an ion.
When using alternating current,
resistance is calculated as impedance (Z).electrical -production can be graphically expressed as a sinusoidal wave.
The turns ratio of a transformer is determined by the
number of windings.
The process of electrons being emitted from heated metallic surfaces is called
thermionic emission.
The material of choice for semiconductors is
silicon.
How many times does an AC current change direction in a single minute?
7,200
Conventional current flows
from anode to cathode.
An electrical device that is designed to store charge momentarily after charging is a/an
capacitor.
American generators operate at
60 Hz.
All of the following are true of transformers EXCEPT:
a.
They have no moving parts.
b.
They work on the principle of mutual induction.
c.
They work most efficiently on pulsating DC.
d.
They are designed to regulate voltage.
They work most efficiently on pulsating DC.
All of the following are true of induction motors EXCEPT:
a.
They use multiphase current and can turn at varying rpm.
b.
Motor power can be regulated by the characteristics of the electromagnets that make up the stator.
c.
Their design is inherently weak with regard to power.
d.
They are used to spin the x-ray tube anode disk.
Their design is inherently weak with regard to power.
All of the following are true of autotransformers EXCEPT:
a.
They are considered a variable transformer.
b.
The primary and secondary coils are in series.
c.
The primary and secondary windings share a common coil.
d.
They are effective in controlling voltage on the high voltage side of the circuit.
They are effective in controlling voltage on the high voltage side of the circuit.
A transformer with more secondary windings than primary windings
has a greater secondary voltage.
A stator consists of
electromagnets.
A simple DC generator has essentially the same construction as an AC generator except that a DC generator employs the use of
a commutator.
A rectifier
converts AC to DC.
A motor is a device that converts
electrical energy into mechanical energy.
A magnetic field is produced by
electric charges in motion.
A generator is a device that converts
mechanical energy to electrical energy
A continuous, expanding and contracting magnetic field is produced by
alternating current.
A bar magnet and a wire loop move with the same linear velocity and direction. The voltage induced in the wire is
zero.
When an electric current flows through a solid conductor (wire) with resistance, energy is
liberated as thermal energy.
The unit of electrical power is the
watt.
The resistance in a wire decreases as its
diameter increases.
