Physic's Unit 1 (lessons 1-14) test review (c

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electrostatics

the area of physics that deals with objects that have an unbalanced electric charge

Static is…

the build up of electric charge on an insulating substance

Current is…

Flow

the movement of electric charge through a conductive substance

conducting spheres…

charge spreads out evenly.

insulating objects…

charge remains stationary

pointed objects…

charge concentrates in an area

who discovered the electron?

J.J Thomson

how did J.J Thomson discover the electron?

using a cathode ray

Who discovered the magnitude of change on an electron and proton?

Robert Millikan

How did Robert Millikan discover the charge of electrons

His oil drop experiment

The elementary charge is…

the smallest possible charge

How many coulombs are on an elementary charge

1.602 × 10^-19

in solids, objects are charged through…

the movement or transfer of electrons between objects

an atom with an excess “-” charge is called a(n)…

anion (electrons > protons)

an atom with a deficit “-” charge is called a(n)…

cation (electrons < protons)

what is the # of charges equation (N)

N = Q / e

(Note: Q represents the total charge and e is the elementary charge)

what are the laws of electric charges?

1. Opposite charges attract each other

2. like charges repel each other.

3. A charged object and a neutral object

   will attract each other opposite

what causes any object to move?

push and pull forces

electric force is…

the force created by charged objects that pushes or pulls objects together

who discovered the relationship between force, charge and the distance between charged objects (Coloumb’s Law)

Charles Coulomb

what is the equation for electric force, F_e (units: Newton, N)

k*q₁*q₂ / r²

(Note:

• k = coulombs constant = 9.00 × 10⁹ N*m²/C²

• q1, q2 = total charge on the object = (coulomb, C)

• r (or d) = distance between the objects’ centres (meters, m)

the relationship between electric force (Fe) and charge (q1, q2) is …

what relationship is Direct

the relationship between electric force and distance is…

inverse square

what uses DC?

Batteries and all electronic devices use DC

in DC electrons only move in…

one direction

in DC, the amount of current

always constant

In DC, will electrons travel the entire pathway?

yes

what uses AC?

the wall socket

in AC the electrons move in…

both directions

In AC, the amount of current…

always varies

In AC, will electrons travel the entire pathway?

no

Note: electrons do not travel the entire pathway in AC

power is…

rate of work

resistance is…

impeding force

impedes the force of electrons travelling in a circuit

electric potential is…

force/pressure

conventional current (electric current) is the…

POSITIVE FLOW of charges

electron flow is the…

NEGATIVE FLOW of charge

what is the current (I) equation?

= ΔQ / ΔT

Note: Electric current (I) , change in charge (ΔQ), change in time (ΔT)

electric potential is the…

the force/pressure that pushes the electrons around the circuit

greater voltage =…

Greater force = brightertransferring lights

forces while pushing and pulling are…

transferring energy

how come birds can sit on a wire

because there is no difference in electric potential in their 2 feet

light bulbs are called…

loads

batteries are called…

cells

electrons will only flow if there is a change in electric potential called…

potential difference

change in energy (ΔE) equation is…

ΔE = Q * ΔV

Note: energy in Joules (ΔE) , Charge in coulombs (Q), potential difference in volts (ΔVcoulombs)

amount of energy equation is …

E = V * I* ΔT

ways to reduce the resistance in a wire include…

• decrease tom vibrations → usually by decreasing temperature

• the type of materials

• a larger diameter of wire

• a shorter length wire

what causes resistance?

• gretaer attarction = greater resistance

• more frictrion = resistance

why are incandescent light bulbs filled with argon gas and not “normal” air?

normal air has oxygen, which can lead to fires

what is the power (P) equation?

• ΔE / Δt

• V * I

• I² * R

• V² / R

1. change in energy (ΔE)

2. change in time (Δt)

3. electric power in watts (P)

4. resistance in ohms (R)

5. the potential difference in voltage (ΔV)

1 watt is…

1 joule / second

cost of electricity equation is,,,

P * Δt

total cost equation is…

C * P * ΔT

note : C = cost of electricity

Giga (G)

10^9

Mega (M)

10^6

Kilo (k)

10³

Hecto (h)

10²

Deka (da)

10^1

Deci (d)

10^-1

Centi (c)

10^-2

Milli (m)

10^-3

Micro (µ)

10^-6

Nano (n)

10^-9

Current is measured in…

Amps (A)

the relation between current and time for DC is…

a horizontal line

the relation between current and time for AC is…

a sine graph

What is the relationship in words between V, I, R,.

In a circuit, Ohm's Law states V (voltage) is directly proportional to I (current) when R (resistance) is constant.

What is the equational relationship between V, I, R

V = I * R.

What is the relationship graphically between V, I, R,

a straight line with a slope equal to resistance R.

What are the 4 main terms of current electricity

• Power - Rate of work

• Electric Potential - Force/Pressure

• Current - Flow

• Resistance - Impeding Force

What is worse 10 amps or 10 volts ?

10 amps is worse than 10 volts. Amps determine the strength of the electric current flowing through the body, while volts measure the electrical potential. So, a higher amperage can lead to a more severe shock.

Do lightning rods attract lightning?

No! They provide a path for an electric charge that is already in the vicinity

Battery drain equation?

Capacity = Time * I (current)

How do i find resistance with a multimeter

Basic parts of a circuit

• Load

• Source

• Connectors

• Control devices

If each cell is 1.5 volts and has a capacity of 200mAh, what would the total voltage and total capacity of the battery be?

• Total Voltage: 4.5 V

• Total Capacity: 200mAh

Note: This is because in series, batteries voltage increases by the amount of cells present (each repeating long and small line pattern). And the capacity stayed the same.

If each cell is 1.5 volts and has a capacity of 200mAh, what would the total voltage and total capacity of the battery be?

• Total Voltage: 4.5 V

• Total Capacity: 400mAh

Note: This is because in parallel, batteries voltage increases by the amount of cells present in a parallel circuit, so by 3. The capacity increases by the set of parallels which is 2.

batteireis in series ….

add their voltage together

while batteries in parallel …

do not add their voltages together

What did Alessandro Volta do?

He is credited with making the first electric potential cell or voltaic pile AKA battery.

bigger batteries =

more capacity

Primary batteries

one-and-done single-use batteries

Secondary Batteries

reversible in their chemical reactions and hence rechargeable

Why are Solid State Batteries better than conventional batteries?

• higher energy density

• lasts longer

• limited temperature issues

• faster charging rate

• reduced fire hazards

what is the equation used when adding resistors in series?

R0 = R1 + R2 + R3…

what is the equation used when adding identical resistors in parallel?

R0 = R1/n

what is the equation used when adding different resistors in parallel?

1/R0 = 1/R1 + 1/R2…

what is the graphical relationship between resistance and current?

inverse (squared)

R a I

what is the graphical relationship between resistance and voltage

Direct

R a V

what is the graphical relationship between current and voltage?

direct

I a V

What is Kirchhoff’s Voltage law in series?

The electric potential increase and decrease sums along any complete path must be equal.

less resistance =…

more flow

what is Kirchhoff’s Voltage law in parallel?

the potential difference between any 2 paths in parallel must be the same

What is Kirchhoff’s current law?

At any junction in a circuit, the amount of current that goes in must be equal to the amount of current that comes out