MOD 1

• What are protons made of?

  Quarks
• Do Quarks have the charge for protons?

  Yes
• Are quarks smaller than a proton?

  Yes
• $N=$$Q/e$


  N= Excess protons

  Q= Charge

  e=$+$$- 1.6 X10^4$
• Charge is quantized meaning?

  That it has fixed indivisible units.
• When charge, Q moves from one region to another region, electrical current is produced.
• Some current is steady and some vary. Types are:

  Direct current and Accelerating current
• What is Instantaneous current?And its formula?

  Current at a specific moment, in small amounts.

  $I=$$change in Q/change in t$
• What is the Volt?

  The unit of potential difference and EMF.
• Formula for the volt?

  $V=$$W/Q$
• What is a Conductor?

  A conductor is a material that allows the transfer of charge.
• Types of conductors:

  Metal

  Plasma

  Electrolyte

  Semi-Conductor
• A Metallic conductor is held together via a metallic bond, in the lattice structure there are liberated electrons. These electrons form a convection band.(range of energy levels for current conduction) The free electrons bombard the fixed lattice positions and cause the ions to vibrate and produce heat.

  
• Label the Graph:

  A) Electron hits an ion here

  B) Electron loses K.E

  C) Electron gains K.E

  
• Label the parts:

  A) I

  B) I

  C) L

  D) A

  E) Cross- sectional area

  F) Length parallel to current

  G) Current

  H) number density of electrons

  I) Charge of electron

  J) Avg Velocity of the electron

  
• Formula for current in a conductor:

  $I=$$nevA$
• Derive $I=$$nevA$


  If Volume= L x A and N'= total number of electrons

  And N'= n x V

  Then N'= n x LA

  If Q= nLA x e

  And current, I= Q/t

  Then I= nLAe/t

  And V= L/t

  Therefore I=nevA
• What is current density?

  Current density is defined as electrical current per unit cross-sectional area and is therefore given as $J=$$ven$ for a metallic conductor
• What is Plasma?

  Plasma is defined as ionized air. When the air's temperature increases, is subjected to magnetic fields, strong electrical fields or the energy photons increase, it becomes IONIZED. And it becomes Plasma.
• Where is plasma found?

  In flames, neon lamps, lightning bolts, stars and aurora in the upper layer of the atmosphere.
• Why is plasma the best conductor?

  In the metallic bond, the ions are closer than the molecules in a gas. They are more resistant to motion of the charges than in metallic bonds.

  Plasma has both positive and negative particles that move in opposite directions.
• Label parts below:

  A) 0.003

  B) Ion

  C) not

  D) drift

  E) around

  F) repulsion

  G) repulse

  
• What is drift velocity?

  The average velocity at which an electron drifts in the presence of an electric field.
• Conventional current concept.

  A) opposite

  B) electron

  C) large

  
• What is an electrolyte?

  An electrolyte is compound that can separate ions when in solution or molten.
• An electrolyte contains positive and negative ions that are free in motion throughout the liquid. It is as good a conductor as metals.
• What the net formula for current?

  $I=$$(nevA)+$$(nevA)$
• What is resistance?

  It is the opposition to the free movement of charge.
• In a semi-conductor has positive charge carriers called holes and negative charge carriers called electrons.
• What is the formula for resistance?

  $R=$$V/I$
• What is the ohm?

  The ohm is defined as being the resistance of a conductor through which current of one ampere is flowing when the potential difference across it is one volt, that is $1ohm=$$1VA^-$$^1$
• A semi-conductor has $10^2$$^1$ electrons per 𝑚3 and a metal has $10^2$$^8$electrons per 𝑚3. A semi-conductor has a lot less electrons than a metal.
• What type of conductor is this?

  A) Ohmic

  B) V=IR

  C) Temperature

  
• What type of conductor is this?

  A) Filament lamp

  B) R increases

  C) T increases

  
• What type of conductor is this?

  A) Semi-Conductor Diode

  B) Reverse Bias

  C) Forward Bias

  D) R=Infinite

  E) R=0

  F) Not symmetrical

  
• What is a thermistor?

  A thermistor is a resistive device, whose resistance changes with temperature.
• Types of Thermistors:

  Negative temperature coefficient (NTC)and Positive temperature coefficient (PTC)
• NTC and PTC are made of ceramic and polymer materials.
• What is this symbol:

  A) Thermistor

  
• What type of thermistor graph is this?

  A) NTC

  B) A.C

  C) Temperature

  D) circuit boards

  E) T increases

  F) R decreases