03 - Fundamentals of Electricity Flashcards
In an atom, the electrons are _______ (positively/neutrally/negatively) charged
Negatively
In an atom, the protons are _______ (positively/neutrally/negatively) charged
Positively
In an atom, the neutrons are _______ (positively/neutrally/negatively) charged
Neutrally
In a process called “ionization,” an atom may lose an electron and become ________ (positively/negatively) charged
Positively
Name two ways in which electrons can be moved
Friction
Heat
Chemically (e.g. batteries)
Magnetic (e.g. Power generation)
A neutral atom with a full outer shell would be a good _______ (conductor/insulator)
Insulator
In a battery, the _____ (cathode/anode) is positively charged and made of a material that readily _____ (gives up/accepts) an electron
Cathode, gives up
Like charges ______ (attract/repel) and opposite charges _____ (attract/repel)
Like charges repel
Opposite charges attract
What is a Coulomb (C)?
A metric measure of electrical charge
Q = number of protons or electrons x (1.602x10^-19)
What is Voltage (V)?
Electrical pressure measured in volts
V = Work (joules) / Charge (coulombs)
By convention, current is shown going from ______ to ______, which is opposite to the flow of electrons
Positive to Negative
What is Current (I)?
The rate of flow of electrons
I = Q/t
Coulombs/sec or Amperes (amps)
What is Power?
The amount of work done per second
Power (watts) = V x I
What are the two types of current?
Direct Current (DC) (e.g. battery) and Alternating Current (AC) (e.g. 60 Hz wall socket) -AC is shown as a sinusoid, DC has a constant voltage
Current flowing through a wire creates a ______ (electrical/magnetic) field around it
Magnetic field
*A changing magnetic field can induce current in a conductor
True or False: using the Right Hand Rule shows your thumb pointing in the direction of CONVENTIONAL current, and your fingers indicating the direction of the MAGNETIC field
True
What are 2 examples of wireless energy transfer (e.g. changing the current in a loop, therefore changing its magnetic field, which changes the magnetic field of a second loop, inducing a current there)?
- hearing aid telecoils
- cochlear implants
- power supplies (wireless chargers for cellphones, powering the chip in your credit/debit card using Tap to pay)
Fill in the blanks for the energy transfer used in hearing aid telecoils:
Acoustic -> ______ -> Magnetic -> ______ -> _______
Acoustic -> ELECTRIC -> Magnetic -> ELECTRIC -> ACOUSTIC
What is the main advantage of using a telecoil for a hearing aid instead of just amplifying the sound in the room?
Quality of the sound - the magnetic field is not influenced by reverberation, just the SPLs at the microphone
Describe how a loudspeaker uses electromagnetic principles to transfer an electrical signal back into an acoustic signal
- Loudspeaker has a permanent magnet that doesn’t move
- Alternating Current through suspended voice coil creates an alternating magnetic field, which goes through periods of attraction and repulsion with the permanent magnet
- Voice coil is also attached to the diaphragm and this push/pull of attraction with the permanent magnet moves the diaphragm, creating sound pressure waves
Good ________ (conductors/insulators) have tightly bound electrons
Insulators
Name 2 examples of good conductors
- copper
- gold
- silver
- platinum
What’s a semiconductor?
A semiconductor is somewhere between insulators and conductors
- used in solid state devices
Resistance (R) quantifies the amount of resistance offered to the flow of electrons. Using Ohm’s Law, state the equation for resistance
R (ohms) = V (volts) / I (amps)
