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111 terms

The rate of flow of electric charges

current

What is the symbol for current? Unit?

I, Amperes (A)

In a current, how do charges move?

Randomly

Electric currents when connected to a potential difference, it creates a(n) _ field which creates a(n) _ force setting _ in motion

electric, electrical, charges

What do batteries and generators have to do to charge carriers?

work/supply energy

What do batteries and generators set up across a circuit?

a potential difference

Batteries convert what to what?

chemical PE to electrical PE

Generators convert what to what?

mechanical energy to electrical PE

Do batteries and generators give the circuit charges?

no

Since batteries and generators don't give the circuit charges, the just...

force the charges to move in one direction *note, the electrons are already on the wire

Electrons flow from (positive/negative) to (positive/negative)

negative to positive

The electrical force _ the electrons to/from the positive terminal and the electrons are _ to/by the negative terminal

attracts, repelled

Electrons move from an area of (high/low) electric potential to an area of (high/low) electric potential (AKA voltage)

high, low

How does the flow of current in batteries work?

The negative terminal loses negative charge and eventually becomes positive. The positive terminal gains negative charge and eventually becomes neutral. Once the charges even out, there is no longer a potential difference between them, and the flow of electrons (current) stops

The direction that positive charges would flow (if they did flow)

conventional current, positive to negative

Which way does conventional current flow?

from positive to negative

The direction that electrons (negative charges) would flow

Actual current, negative to positive

Which way does actual current flow?

from negative to positive

Do you know how to draw pictures of both conventional flow notation and electron/actual flow notation?

yes

The opposition to the flow of current in a conductor

Resistance

The higher the resistance, the _ current can make it through

less

What is the symbol for resistance? Unit?

R, Ohms (Ω)

Put in a circuit to control (slow) the flow of current

resistor

Materials that have a resistance of zero

superconductors

What are the three factors affecting resistance?

length, cross-sectional area, and conductivity

Longer length = _ resistance, shorter length = _ resistance

more, less

What is another name for cross-sectional area?

thickness

The smaller the area (or thinner) = _ resistance, the larger the area (or thicker) = _ resistance

more, less

What is another way to explain conductivity?

the type of material used

Higher conductivity = _ resistance, lower conductivity = _ resistance

low, high

For most conductors, the amount of resistance remains constant. This is...

Ohm's law

The amount of current that flows through a circuit is _ly proportional to the voltage supplied to the source

directly

The amount of current that flows through the circuit is _ly proportional to the resistance of the conductor

inversly

The rate at which energy is converted from one form to another

power

What is the derived power formula that you are not given?

P=I^2R

What is the derived energy formula that you are not given?

E=ΔVIT

What is the symbol for power? Unit?

P, Watts (W)

Power times time

Energy

What is the symbol for energy? Unit?

E, Joules (J)

Energy per unit of time

power

Does a high powered light bulb put out a lot or a little of light per second?

a lot

One joule per second is also known as a...

watt

One coulomb per second is also known as a...

amp

When you multiply voltage times current, you get _

power

In a 120 volt electrical outlet, every Coulomb of charge does _ Joules worth of work as it moves from one side of the outlet to the other

120

The ability of a conductor to store energy in the form of electric charge

Capacitance

What is capacitance measured in?

Farad

Pico is...

-12

Micro is...

-6

An electrical device that stores electrical charge and energy which can be removed for use at a later time

Capacitor

Two conductors, separated by an insultar. Acts as a storehouse of charge that can be reclaimed when needed

capacitor

Used in electronic devices to maintain power supply while batteries are being charged, prevents memory loss

capacitor

Thing where plates are connected to a potential difference (voltage source) such as a _

parallel-plate capacitor, battery

How do parallel-plate capacitors work?

charge is removed from one plate and collects on the opposite plate

When do charge transfers stop in parallel-plate capacitors?

when the potential difference of the plates equals the potential difference of the battery it's connected to

How is discharging done in a parallel-plate capacitor?

by connected the capacitor to a conductor via a switch (ex. flash of a camera)

All schematic diagrams are drawn using which current?

conventional

What condition is necessary for the flow of heat? What analogous condition is necessary for the flow of charge?

temp difference, potential difference

What is meant by potential difference? What does a potential difference produce in a circuit?

voltage, current

What conditions are necessary for the sustained flow of water in a pipe? What analogous condition is necessary for the sustained flow of charge in a wire?

pressure difference, potential difference

What is electric current?

flow of charge/moving of electrons

What is an ampere?

unit of current (1 C/s)

What is a volt?

potential difference (1 J/C)

How many joules per coulomb are given to charges that flow in a 120-volt circuit?

120 v

Does charge flow through a circuit or into a circuit?

through (electrons already on wire)

Does voltage flow through a circuit, or is voltage established across a circuit?

established across

What is electrical resistance?

resists current

If the voltage impressed across a circuit is constant but the resistance doubles, what change occurs in the current?

cut in half (inverse)

If the resistance of a circuit remains constant while the voltage across the circuit decreases to half its former value, what change occurs in the current?

cut in half (direct)

How does wetness affect the resistance of your body?

resistance decreases

Distinguish between AC and DC. Which is produced by a battery and which is usually produced by a generator?

alternating current in generators or outlets (2 way), direct current in batteries (1 way)

From where do electrons originate that flow in a typical electric circuit?

on the wires or conductors

What is power?

the rate of doing work (1 Watt = 1 J/s)

Drawings that represent electric circuits using standards symbols for circuit elements

schematic diagrams

A complete path (loop) which charge can flow

circuit

What are 3 things found in a common circuit?

voltage source (battery, generator, etc), conductor (wire), device to receive electrical energy (light bulb)

In a common circuit electrons flow from _ to _

negative to positive

For a continuous flow of electrons, the circuit must be _ with no _

complete, gaps

What will happen if there is a break in an electric circuit?

here will be a complete stop in the flow of electrons

What is an example of something that can be used to break a circuit?

a switch

Electric current that repeatedly reverses in direction, twice each cycle. Usually at 60 cycles per second

Alternating current

Example(s) of alternating current

generator, outlet

"Two way street"

alternating current

Electric current whose flow of charge is always in one direction

Direct current

"One way street"

direct current

Example(s) of direct current

batteries

What is the primary use of current?

to transfer electrical energy

Which type of circuit allows current to travel great distances with easy voltage step-ups that result in lower heat losses in wire?

AC circuits

What 2 things can be inserted into lines that provide power to prevent overloading?

fuses and circuit breakers

What will excessive current do to the fuse, circuit breaker, and circuit?

blow out the fuse, trip the circuit breaker, and provide a break in the circuit

Resistors are connected such that there is a single pathway for electron flow

series circuit

In a series circuit, what stays the same?

current

What is the formula for the total current in a series circuit?

Vt=ItRt

How do you find the voltage drop across each device in the series circuit?

V1=ItR1 (V2=ItR2, etc)

According to _ Law, in a series circuit there is a voltage drop across each device that depends directly on its _

Ohm's, resistance

Formula for the total voltage in a series circuit

Vt=V1+V2+V3...

In a series circuit, _ is the same throughout each resistor

current

In a series circuit, _ is different through each resistor

voltage

In a series circuit, the parts equal the whole for...

voltage

Resistors are connected such that there are multiple pathways for electrons to flow

parallel circuit

In a parallel circuit, what stays the same?

voltage

What is the formula for total current in parallel circuits?

Vt=ItRt

What do you notice about the series circuit formula for total current and the parallel circuit formula for total current?

same (Vt=ItRt)

What is the formula to find total current in a parallel circuit?

It=I1+I2+I3...

In a parallel circuit, _ is different through each branch (resistor)

current

In a parallel circuit, _ is the same through each branch (resistor)

voltage

In a parallel circuit, _ the parts equal the whole for...

current

Do you know how to find equivalent resistance?

yes

Do you know how to work with complex circuits?

yes

Current is proportional to resistance...

parallel

Voltage is proportional to resistance...

series