Electrical properties Flashcards
What is the unit of charge?
Coulomb (C)
What does the Faraday constant represent?
The charge on 1 mole of electrons.
What is the value of the Faraday constant?
9.648x10^4
What is an electrical field?
A region where an electric force is experienced and can be mapped by electrostatic lines of force.
What is the force on a charged body within an electric field dependent on?
- The charge on the body
- The strength or intensity of the field
What is the unit of potential?
Volt
What is a volt?
The potential difference between two points A and B is one volt if the work done in taking once coulomb of positive charge from B to A is one Joule.
What is potential difference?
The difference in electrical potential between two points.
What can be used to measure membrane potential?
A microelectrode and a reference electrode connected to a potentiometer.
What are conductors?
Anything that can transmit charge.
What are the conductors of biology?
Electrolyte solutions.
What allows for conduction in metals?
Free electrons
What does an electrical field do to free electrons?
Accelerates them so they drift in the direction of the field.
What is the equation for calculating force?
F=1/r^2 (r=distance)
What is the symbol for charge in an equation?
Q
How do ion channels select between cations and anions?
Proteins comprised of negative amino acid side chains allow positive ions to pass through and vice versa.
How does an increase in the number of charges affect potential?
Increases potential
In what direction is a current carried?
From negative to positive
What is a current?
The rate at which charge passes a point in a closed circuit.
What is the unit of measurement for current?
Amperes (A)
What is the symbol for current in an equation?
I
What is resistance?
Opposition to flow through a conductor.
What is the unit of measurement for resistance?
Ohms
What is the symbol for resistance in equations?
R
What is an electrical insulator?
A material that fully prevents current flow.
What is conductance?
The ease with which a charge flows through a conductor.
What is the unit of measurement for conductance?
Siemens
What is the symbol for conductance in equations?
G or g
What does Ohm’s law quantify?
The relationship between potential difference (V), current (I) and resistance (R).
What is the equation for Ohm’s law?
V=IR
What are capacitors?
Electrical devices that store charge.
What is the simplest capacitor?
A parallel plate capacitor where the two plates are separated by a dielectric.
How do capacitors work when connected to a battery?
- electrons flow form the negative terminal to plate A and at an equal rate from plate B to the positive terminal.
- equal positive and negative charges build up on plates and start to oppose electron flow on plate A by repulsion and reduce flow from plate B by attraction.
- charge accumulation on plates generates potential difference which increases to a value equal to that of the battery voltage
- when potential difference across the capacitor (V) is equal to the battery voltage (Vo) electron flow ceases and the charging current equals 0.
What is capacitance (C)?
The amount of charge a capacitor can store.
What is the unit of measurement for capacitance?
Farads (F).
What is capacitance proportional to?
- Surface area of the plates - increases with area.
- Distance between plates - decreases with increased distance (d)
- Properties of dielectric that separates the plates
