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WorksheetsDirect Current Key Terms
Total questions: 45
Worksheet time: 23mins
Current is defined as:
The flow rate of electrons
The total stored charge in a circuit
The opposition to voltage
Matter is:
Anything that occupies space but not mass
Anything that has mass and volume
A form of stored energy
A molecule is:
A charged particle within an atom
The smallest particle of matter that retains its identity
A combination of two atoms only
The smallest building block of matter is:
Molecule
Cell
Atom
The Kinetic Theory of Matter states:
Particles only move in solids
Matter is made of particles that are always in motion
Particles move only when heated
Valence electrons are:
Found in the nucleus
Electrons in the outermost shell involved in bonding
Used only in magnetism
An ion is:
An atom that has gained or lost electrons and has a net charge
An atom that splits into two
An unstable nucleus
A material that allows electrical current to flow freely is a:
Conductor
Semiconductor
Insulator
A material that resists electron flow is:
Conductor
Insulator
Proton
Semiconductors:
Block all electrons
Can act as conductors or insulators
Are only found in batteries
Static electricity is:
Electrons at rest with no current flow
Electrons in motion
A type of magnetic bonding
Dynamic electricity refers to:
No movement of electrons
Electrons in motion generating current
Only DC
Magnetism is:
The ability to store electrons
The property of attracting iron and producing a magnetic field
A light-based process
Magnetic flux lines represent:
Heat flow
Lines of magnetic force
Electric resistance
Reluctance is:
Ability to conduct electricity
Opposition to magnetic flux through a material
Work output of a motor
An electromagnet is:
A magnet created by current flowing through a coil
A natural magnet
A magnet that cannot be turned off
Conventional current flow is:
Positive to negative
Negative to positive
Around the nucleus
Electron flow is:
Positive to negative
Negative to positive
Always clockwise
Piezoelectric effect is:
Voltage generated when a crystal is mechanically stressed (pressure)
Light causing electrons to move(light)
Heat causing voltage(thermal)
Thermocouple:
Joined dissimilar metals producing voltage when heated
Converts voltage to heat
Stores heat
Electromotive Force (EMF) is:
The electrical force that causes electrons to move; measured in volts
The force of magnetism
The resistance of current
Ohm’s Law defines:
Thermal current theory
The relationship between voltage, current, and resistance
Battery composition
Resistance is:
The opposition to current flow
Force of voltage
Voltage divided by watts
A rheostat:
Device to divide voltage
Variable resistor used to control current
A switch
A potentiometer:
Variable resistor used only for current
Variable resistor used to divide voltage
A fuse
A photoconductive cell:
Changes resistance with temperature
Light-controlled variable resistor
Stores electrons
A direct short is:
Wires touching directly, bypassing intended path, causing fast heating
Low voltage
High resistance fault
A fuse:
Tin-bismuth alloy element that melts when current is too high
Device that must be reset manually
Magnetic safety device
A current limiter:
Copper device that withstands brief overload and protects bus systems
A resettable breaker
A temperature device
A circuit breaker:
Opens during overload and must be manually reset
Melts when tripped
Cannot reopen
A switch:
Used to start, stop, or redirect current
Stores energy
Divides voltage
A relay is:
A remotely actuated electromechanical switch
A fuse
A resistor
In a thermal circuit breaker:
A magnet opens the breaker
A bimetallic strip heats up and opens the breaker
A fuse melts to open the circuit
Thermal protectors are used to:
Protect motors by opening the circuit automatically when temperature is excessive
Replace fuses during overload
Stop voltage generation in generators
In a DC generator, brushes:
Rotate with the coil
Are stationary contacts that transfer current from the commutator
Generate mechanical motion
A magnetic field around a current-carrying conductor:
Does not form unless grounded
Forms automatically when electrons move
Can only form in permanent magnets
The strength of an electromagnet depends on:
Voltage only
Current, number of loops, and core material
Shape only
Induction is:
Electrons stopping movement
Transfer of electrical energy without means of connections
A chemical reaction
An inductor(coil) is:
A wire bent into many loops
A single straight wire
Only found in motors
Free electrons:
Move through materials and enable conduction
Remain stuck to the nucleus
Carry no charge
The kinetic theory states:
Particles of matter are always in motion
Particle motion only occurs in gases
Particle motion only occurs when heated
A compound is:
A chemical combination of two or more elements
A single element
The smallest unit of matter
An element is:
A substance that cannot be chemically reduced further
Two atoms combined
A molecule with charge
Magnetic permeability refers to:
Ease of magnetic flux penetration
Resistance to heat flow
Opposition to electron movement
Reluctance refers to:
Opposition to magnetic flux flow
Stored electrical energy
Direction of current
