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Static & Electric Charge, Voltage, Circuits & Current, Resistance & Ohm's Law

1

What is static charge?

electrical charge that can be held in one place (static electricity)

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2

How does static charge build up?

2 insulators rub together = friction → e- transferred through materials… now 1+ and 1-

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3

What is an insulator material?

does not allow charges to move easily. ex: when one end becomes + the other will stay the same

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4

What are examples of insulators?

glass, dry wood, ceramics, plastic, rubber

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5

What is a conductor material?

allows electrons to travel freely.

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6

Why are metals good conductors?

metal atoms have at least 1 valence e- that can transfer.

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7

What material can retain static electricity?

Only insulators since it is held in one place

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8

What are the properties of static charge?

never created/destroyed and charging = moving charge to different places

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9

What is the unit of measurement for electrical charge?

Coulomb (C)

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10

What is an electroscope?

detects static charge

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11

What is a danger precaution about static charge?

Grounding = charge → Earth’s surface

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12

What is a contact force?

apply force only on objects they touch (push/pull)

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13

What are forces that act at a distance?

apply force without touching. Ex: gravitational, magnetic, electric force

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14

What is an electric force?

a push or pull between charged objects

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15

What are the laws of electric force?

1. Opposites attract

2. Same repel

3. Neutral is attracted to charged

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16

What happens to the force if you increase the charge?

it is stronger

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17

What happens to the force if the distance of charged increases?

it is weaker

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18

What is Induction?

transferring electrons with no physical contact

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19

What is conduction?

transferring electrons with physical contact

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20

What is static discharge?

Static charge will dissipate, move into air moisture or spark

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21

What is electric current?

electric charge moving though a wire

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22

What is another name for voltage?

potential difference

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23

What is voltage?

a measure in the difference of energy between two points

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24

How and what is voltage measured in?

Voltmeter (outside circuit) and in volts (V)

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25

When charges/electrons pass through a cell they…

gain potential energy (or the potential to do something)

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26

What does an electrochemical cell do?

Converts chemical energy to electrical energy and gives electrons stored potential energy

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27

What are the types of electrochemical cells?

Dry (flashlights) and wet (car)

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28

What are the terminals?

electrodes = metal → anode (-) or cathode (+)

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29

What is the paste/liquid solution in a cell called?

electrolyte

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30

How does a battery produce voltage?

chemical reaction → charges separate in electrolyte but charges attract so it takes energy to pull apart = chemical →electrical energy = the potential for the electrons to move

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31

What is energy and work and its unit?

energy is the ability to do work, work measures the transfer of energy, unit Joules (J)

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32

What is an electrical current?

flow of electrons past a certain point within a time frame

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33

What is current measured in and with what?

Ammeter (in series) ampres→amps (A)

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34

If there is more electrons what is the current?

It is bigger

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35

Does the current change within a circuit?

No

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36

What are the circuit components?

source of electrical energy (cell/battery)

Conductor (wire)

Switch

Load = electrical energy →other forms of energy

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37

What is resistance?

a measure of how much a material tries to stop electricity passing through it

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38

How is there resistance?

electrons collide with metal atoms = vibration → heat

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39

What is a resistor?

reduces current, (also use: transfer electrical energy to heat and light energy)

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40

What affects resistance?

material

length

temperature - decrease = decrease in resistance

thickness - increase = increase in surface area → decreases collisions

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41

What is the relationship between voltage and current?

Voltage increases = current increases

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42

What is the relationship between resistance and current?

resistance decreases = current increases

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43

What is Ohm’s Law?

Voltage = Current x Resistance

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44

What is Ohm’s Law measured with and unit?

Ohmmeter, ohm (Lululemon symbol)

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45

When there is a k before the unit… but when there is an m…

multiple by 1000…divide by 1000

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46

What is a series circuit?

only one pathway for electricity to flow (no branches)

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47

What is a parallel circuit?

more than 1 loop (multiple branches)

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48

What is the formula for voltage in a series circuit?

V(source) = V(load 1) + V(load 2) + V(load3) + …

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49

What is voltage in a series circuit?

each load loses a portion of total voltage, voltage across loads add up to total voltage supplied by battery/cell

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50

What is the formula for current in a series circuit?

I(source) = I(1) = I(2) = …

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51

What is current in a series circuit?

current at each part in circuit is equal to total current supplied by battery/cell

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52

What is resistance in a series circuit?

more resistors = more resistance, if total resistance increases total current decreases

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53

How do you find resistance in a question?

Use Ohm’s Law

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54

What is the formula for voltage in a parallel circuit?

V(source) = V(load 1) = V(load 2) = …

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55

What is voltage in a parallel circuit?

voltage is the same throughout circuit and equal to battery

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56

What is the formula for current in a parallel circuit?

I(source) = I(1) + I(2) + I(3) + …

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57

What is current in a parallel circuit?

divided into pathways that will rejoin , current through each pathway adds up to total current in the battery

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58

What is resistance in a parallel circuit?

when resistors are placed in parallel = another pathway so total resistance decreases = current leaving battery increases

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59

What are the 2 types of energy sources?

renewable = naturally replenished

non-renewable = can’t be replaced by natural means quickly enough to keep up with demand

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60

How do generators work?

Fossil fuels → power stations → burnt = heat energy

Heat energy + water = steam

steam + turbines = generators

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61

What are electrical generators?

a device to turn kinetic energy in turbines to electrical energy

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62

How do electrical generators work?

magnet near wire = flow of electrons/electrical charge, electricity generated →cables → National Grid

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63

How does coal create electricity?

powdered coal blown into furnace

coal burns = water heats in boiler

water → high pressure steam

steam turns turbine

turbine turns shaft connected to generator

generator turns = electricty

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64

What is AC?

alternating current is electrical current produced by generators that can change direction. ex charging phone

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65

What is DC?

Direct current is a source of portable electricity, ex. battery

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66

How does DC work?

stores chemical energy that can change into electrical energy but cells might go flat (run out of chemical energy unless rechargeable

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