Electrical Principles 2 Flashcards
What is the nature of electric charge?
Positive and negative charges interact with each other.
Define electric current.
The rate of flow of charge, measured in amperes (A).
What does the equation I = dQ/dt represent?
It defines electric current (I) as the rate of change of charge (Q) over time (t).
What is voltage (V)?
Voltage is the electrical potential difference, measured in volts (joules/coulomb).
What is Ohm’s Law?
It relates voltage (V), current (I), and resistance (R) as V = IR.
Define resistance.
Resistance is the opposition to the flow of charge, measured in ohms (Ω).
What is conductance?
Conductance (G) is the ease with which charge flows, measured in siemens (S) and is the reciprocal of resistance.
How do you calculate total resistance for resistors in series?
R_T = R_1 + R_2 + … + R_N.
What is the relationship between current (I), voltage (V), and resistance (R) in a series circuit?
The same current flows through each component.
How do you calculate total resistance for resistors in parallel?
1/R_T = 1/R_1 + 1/R_2.
True or False: A potential difference applied across a resistor can be used to calculate current using Ohm’s Law.
True.
Fill in the blank: A capacitor is an electric device that ______.
stores charge.
What is capacitance (C) and how is it measured?
Capacitance is the ability to store charge, measured in farads (F).
What factors affect the capacitance of a capacitor?
- Surface area of the plates (A)
- Distance between the plates (d)
- Properties of the dielectric material.
What happens to current when a capacitor is fully charged?
No current flows around the circuit.
What is the equation for capacitance?
C = ε₀ * ε_r * A/d.
What does ε₀ represent?
The electric constant, approximately 8.854 x 10^-12 F/m.
What is the role of the cell membrane in relation to capacitance?
The cell membrane acts as a capacitor, maintaining a charge gradient.
How is input resistance (R) calculated in a biological context?
R = V/I, where V is the change in membrane potential and I is the injected current.
What is patch-clamp electrophysiology?
A technique to record bio-electrical currents across a cell membrane while controlling membrane voltage.
What is patch-clamp electrophysiology?
A high resolution electrophysiological recording method that allows recording of bio-electrical currents across a cell membrane while controlling membrane voltage.
Who developed patch-clamp electrophysiology?
Bert Sakmann and Erwin Neher.
In whole-cell mode of patch-clamp, what is recorded?
Currents derived from multiple channels/receptors.
In single channel mode of patch-clamp, what is recorded?
Currents that flow through a single receptor channel.
