Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
100 Cards in this Set
- Front
- Back
|
What is electricity?
|
The collection or flow of electrons in the form of an electric charge
|
|
|
What is electrical charge?
|
a property of protons and electrons
|
|
|
When can we say that an atom is neutral?
|
when there is an equal amount of protons and electrons
|
|
|
What is charge?
|
the feeling of a push or pull between 2 electrically charged particles
|
|
|
What unit is charge measured in, and what does 1 of it represent
|
1 coulomb = 6.25 x 10^18
|
|
|
When do objects repel and when do they attract?
|
when there are 2 opposite charges, there is an attraction, but when there are 2 of the same charge, they repel
|
|
|
What is the electrical force?
|
the force that one feels either repelling or attracting
|
|
|
When is the charge of an object changed from neutral to either positive or negative?
|
When electrons transferring
|
|
|
What is a conductor?
|
objects made of metal that allow electrons to flow through them which means that they want to get rid of any extra electrons on the valence shell
|
|
|
What is an insulator?
|
a substance, typically a non-metal, that will take electrons and prevent them from flowing through an object
|
|
|
What is the relationship between conductors, insulators and metalloids?
|
a good conductor is a bad insulator and vice versa --> metalloids are inbetween a good conductor and a good insulator
|
|
|
What is an electrical field?
|
the space that surrounds an electrically charged object, where forces are felt (either attracting or repelling)
|
|
|
What is static electricity?
|
when electrons are transferred to an object and remain stationary (at rest)
|
|
|
What does the rubbing of 2 objects do?
|
it causes electrons to be transferred from one object to another, leaving one object negative and one positive
|
|
|
What is the tribolectric series?
|
What helps us find out which object will gain and lose electrons
|
|
|
What is charging by conduction?
|
when one object that is charged touched another that is neutral, the electrons spread evenly (decrease in electron concentration)
|
|
|
What is charging by induction?
|
when a charged object is brought close to a neutral one, the electrons repel each other and move away from each other, leaving the protons in their original place so that the force of attraction exists
|
|
|
What is the formula for electrical force with units?
|
Fe = (k(q1q2))/r^2
Fe = electrical force in N q1 = charge of the first particle in C q2 = charge of the second particle in C k = coulomb constant |
|
|
What is coulomb's constant?
|
9 x 10^9 Nm^2/C^2
|
|
|
What does coulomb's law only apply to?
|
stationary objects/ at rest (static)
|
|
|
What is dynamic electricity?
|
when electrons are constantly flowing through a conductor, and as a result will produce a current that is in a closed circuit
|
|
|
What is current intensity?
|
the number of coulombs passing through a specific point in a circuit every second (the number of amps)
|
|
|
What is electrical current?
|
the movement of negative charges (electrons) in a circuit
|
|
|
What is the formula for current with the units?
|
I = q/Δt
I = current in A q = charge in C Δt = charge in time in s |
|
|
What is potential energy?
|
the amount of electrical energy the electrons have at any point in a circuit. as they move, the electrons transfer energy into other forms. this means at any 2 points, the electrons have different amounts of energy
|
|
|
What is the formula for potential difference with units?
|
V = E/q
v = volts (v) E = energy (j) q = charge (C) |
|
|
What is resistance?
|
the opposition to the flow of an electric current, causing electrical energy to be converted to thermal energy, or light (usually)
|
|
|
What 4 factors affect resistance?
|
1) the size of the opening
2) length of the conductor 3) temperature 4) material |
|
|
The ______ the distance, the less resistance, the ______ the size of the opening, the less resistance, the ______ conductive the material, the less resistance, the _______ the temperature f the material, the less resistance.
|
- shorter
- larger - more - colder |
|
|
What is the formula for resistance with the units?
|
1Ω = 1V/1A
Ω = ohm (omega sign) V = volts A = amps (I) |
|
|
What is electrical power?
|
the amount of work an electrical device can perform per second.
|
|
|
What are the 2 formulas for electrical power?
|
Pe = VI
Pe = W/t Pe = electrical power (watts) v = voltage (volts) I = intensity (amps) w = work (joules) t = time (seconds) |
|
|
What unit is electrical power measured in?
|
watts
|
|
|
For electricity to flow, it must be within a ______ circuit. Why?
|
A closed circuit because an open circuit is a broken one.
|
|
|
What 3 components must all electrical circuits contain?
|
1) power supply
2) 1+ elements that use electrical energy 3) wires that carry charges in a loop |
|
|
What is a series circuit?
|
a circuit in which all elements are connected from end to end
|
|
|
In a series circuit, if one part is defective, what effect does it have on the rest of the circuit and why?
|
the circuit will become defective because the charges can no longer flow
|
|
|
What is a parallel circuit?
|
a circuit that contains at least one branch
|
|
|
In a parallel circuit, if one part is defective, what effect does it have on the rest of the circuit and why?
|
the circuit can continue functioning due to the other branches
|
|
|
Why is resistance not summative in a parallel circuit, contrary to in a series circuit?
|
because each resistor is being shared amongst all the paths, therefore the total resistance drops
|
|
|
What are Kirchoff's 2 laws?
|
1) current: the current that flows into a node is the same as the current that flows out of it
2) voltage: the total energy acquired by the charges from the power supply is equal to the total energy transferred by the charges, no matter which pathway |
|
|
What are the 3 formulas for a series circuit?
|
1) Vtotal = V1 + V2 + V3...
2) Req = R1 + R2 + R3... 3) I1 = I2 = I3... |
|
|
What are the 3 formulas for a parallel circuit?
|
1) Itotal = I1 + 12 + I3...
2) Req = (1/R1 + 1/R2 + 1/R3...)^ -1 3) V1 = V2 = V3 |
|
|
What is a magnet
|
an object that can attract other objects that contain either iron, nickel or cobalt
|
|
|
The more aligned the domains are, the ______ the magnet
|
stronger
|
|
|
North attracts ______, South repels _______ and North repels _______
|
south, south, north
|
|
|
What 2 poles are all magnets made up of?
|
north and south
|
|
|
What is a magnetic field?
|
the area in which 2 magnets can interact (attract or repel)
|
|
|
In which direction do field lines always move, aside from inside the magnet?
|
north to south
|
|
|
What is magnetic force?
|
the force of attraction or repulsion between magnets
|
|
|
What is the difference between natural and artificial magnets?
|
natural: magnetite artificial: exposing a ferromagnetic object to a magnet magnetizes it.
|
|
|
What does ferromagnetic mean?
|
a substance with the ability to acquire magnetic properties (iron, cobalt or nickel)
|
|
|
When does a material have a magnetic remanence?
|
when it has the ability to acquire and keep magnetic properties
|
|
|
What is non-magnetic?
|
a substance that does not acquire magnetic properties
|
|
|
What are the 2 types of ferromagnets and what are the differences between them?
|
1) temporary magnets: acquire and lose magnetic properties easily (domains can easily unalign --> low magnetic remanence)
2) permanent magnets: difficult to magnetize and demagnetize (high magnetic remanence) |
|
|
How does a magnet demagnetize?
|
a strong sharp hit, heat, or if it in placed in a magnetic field of opposite polarity
|
|
|
What is electromagnetism?
|
magnetism produced by an electric current
|
|
|
Under what conditions can a non-magnetic metallic object create a magnetic field?
|
the electrons must always be in motion
|
|
|
Is an electric field created with dynamic or static electricity? Explain.
|
dynamic because once the current stops, the magnetic field is lost
|
|
|
Explain the right hand rule for an electrified/live wire.
|
you wrap your ands around the wire with your thumb pointing in the conventional current direction and the direction of your fingers is the direction of the magnetic field lines
|
|
|
Explain the right hand rule for a solenoid.
|
align your 4 fingers in the direction of the conventional current and your thumb will be pointing North
|
|
|
Is there North or South in 1 wire examples?
|
no
|
|
|
What is a solenoid?
|
a coiled up version of a live wire
|
|
|
Where is the intensity of the magnetic strongest in a solenoid and in a live wire?
|
solenoid: in the middle
live wire: on the ends |
|
|
Can the intensity be charged in a solenoid?
|
yes
|
|
|
In what case can the magnetic field be turned on and off?
|
in a solenoid, not a magnet
|
|
|
What is an electromagnet?
|
solenoid + ferromagnet
|
|
|
What happens when an electric current is passed through a coil of wire wrapped around a magnetic core?
|
a very strong magnet with a very strong magnetic field is produced
|
|
|
What are 3 ways that an electromagnet can be increased?
|
1) increase the current in the solenoid
2) add more loops to the solenoid 3) use a metal core with a low remanence so the domains can be easily aligned |
|
|
What is electrical engineering?
|
the branch of engineering responsible for designing and developing electrical objects
|
|
|
What are the differences between an electrical device and an electrical appliance?
|
device: stored energy, made of semi-conductors, electronics, usually small, low intensity currents, electrical conduction is controlled by a transistor
appliance: plugged in, continuous flow of electricity, made of conductors, larger, high intensity currents, conduction is controlled to a lesser degree |
|
|
What is alternating current?
|
electricity flowing in one direction, ad then it goes backwards --> an electric current in which the electrons move back and fourth in a regular pattern
|
|
|
What is direct current?
|
in a circuit, the electrons leave the battery and flow through the light bulb --> after, the electrons flow back to the battery in a continuos loop (electrons are flowing in 1 direction)
|
|
|
What is power supply?
|
a circuit component that generates/provides the energy that makes the current flow
|
|
|
What are the 3 types of power supplies?
|
batteries, electrical outlets and photovoltaic cells
|
|
|
What does a battery do?
|
-transforms the energy from a chemical reaction to electrical energy, portable, needs to be replaced often, toxic for the environment, used in watches, remote controls, ipods...
|
|
|
What does an electrical outlet do?
|
designed to receive the prongs of electrical plugs, permanently connected to electrical networks, stable, long lasting power supply, must be plugged in, used in tv, fridge...
|
|
|
What does a photovoltaic cell do?
|
solar cell, when light hits the cell, the electrons begin to move, creating electricity, can be used in areas without access to a power gird, no greenhouse gases, can last 20-30 years, dependant on sunny weather, cost;y, used in calculators, cars, some homes...
|
|
|
What is conduction?
|
The movement of of electrical current, most commonly along electrical wires (often copper)
|
|
|
Why are conductive wires insulated?
|
to avoid short circuits and shocks
|
|
|
Why would a computer short circuit after having coffee spilt on it?
|
because coffee is an acid (electrolyte) that is a good conductor
|
|
|
What is a printed circuit?
|
a miniature electrical circuit printed on a solid support called a circuit board --> boards can be layered and separated by insulating materials
|
|
|
What is a protector?
|
any component in an electrical circuit that can automatically cut current flow in the event of a power surge
|
|
|
What is an insulator?
|
any component that prevents electrical current from flowing (prevents short circuits)
|
|
|
What is a fuse?
|
a protective device --> when too much current flows, the fuse has a metal strip that melts, or snaps, stopping too much current from flowing and frying the device --> once broken, it must be replaced
|
|
|
What is a breaker?
|
something that can be reset many times --> there are 2 central types:
1) bimetallic trips = when the current is too high, the strip heats and bends, stopping the current, and throws a switch off 2) electromagnetic mechanisms = when the current is too high, a switch is flipped to disconnect the contact, immediately preventing the flow of electricity |
|
|
What is resistance?
|
any component designed to limit the flow of electrons in an electrical circuit (ohms)
|
|
|
What is control?
|
the electrical function performed by any component that can open and close a circuit
|
|
|
What are the 4 main different types of switches (with diagrams)
|
|
|
|
What is a capacitor?
|
a device designed to store electrical charge (composed of 2 surfaces/metal plates separated by an insulating material called the dielectric
|
|
|
What unit is capacitance measured in?
|
farads (F)
|
|
|
What would happen if a capacitor was attached to a power supply?
|
the electrons would be unable to move and could not bridge the gap due to the insulating material. if the insulator was removed, an electrical discharge would occur
|
|
|
Why are capacitors used to stabilize a fluctuating power supply?
|
because if the voltage in the circuit drops, the capacitor will release charge to restore the voltage
|
|
|
What is a diode?
|
it allows the circuit to only flow in 1 direction (a checkpoint made of Si)
|
|
|
Why may diodes be electroluminescent?
|
light emitting diodes (LED) give off light when a current flows through them --> consumes less energy
|
|
|
What are the 4 components that can convert/transform electrical energy into another type of energy?
|
incandescent light bulbs, heating elements, piezoelectric crystals and electromagnets
|
|
|
What is an incandescent light bulb?
|
electrons flow through a tungsten filament, which heats and gives off white light (radiant energy)
|
|
|
What are heating elements?
|
electrons resisted by a material, which warms, converting electrical energy into thermal energy
|
|
|
What are piezoelectric crystals?
|
when current is applied to them, it starts to vibrate (mechanical and sound energy) at a very specific rhythm and vice versa
|
|
|
What are electromagnets?
|
electrons flow through coiled up wire wrapped around an iron core (magnetic energy)
|
