Electricity Flashcards
Conventional current is the movement of _____ charges.
positive
Identify the following symbols:
- alternating current
- battery
- amplifier
- amplifier 2
- capacitor
- capacitor 2
- resistor
- resistor 2
Identify the following symbols:
- inductor
- transformer
- circuit breaker
- fuse about to blow
- ground
- ground 2
- diode
- meter
- transistor
- rectifier
- wire
Identify the following circuits:
open circuit
closed circuit
short circuit
What is defined as the “flow of charges per unit time”?
current
What does the symbol with “A”? represent?
ammeter
Definition: potential difference which is the potential energy required to move a charge of one coulomb from point A to point B.
voltage
What does the symbol with “V” indicate?
volt meter
V = IR is known as what law?
Ohm’s Law
Pressure (P) of voltage units:
dynes/cm2
Flow of current units:
cm3/sec
Heat flow (q) unit
Watts
Solute concentration units?
Solute flow units?
mg/ml
mg/min
The corollary to Ohm’s law is known as _____ law.
Ohm’s Law: V = IR
Darcy’s Law: P = QR
What type of current varies around zero?
AC
What depiction most represents the cardiovascular system?
DC + AC shows varying around a mean pressure
This waveform depicts what?
arterial blood pressure waveform
How is the mean pressure or the arterial pressure obtained?
Calculated as the area under the curve.
frequency =
What are the units?
1/T
where T = period
Hertz
If HR = 120 beats per minute, calculate frequency.
2 Hz
Period (T) can also be measured on a graph as distance from ____________.
peak-to-peak
Coulomb’s Law =
Force = Coulomb’s constant (charge strength/distance2)
Note:
- Opposite charges repel and vice-versa.
- If force is (+) = charges are repelled
- If force is (-) = charges attract
Current produces a magnetic field.
If a current is moving in your direction, a magnetic field can be detected. How do you determine the direction of this field?
right hand rule
fingers move in the direction of curled fingers
Current flows in direction of ___ charge flow.
positive
Wires that are near each other, they will have magnetic field around them. Why will wires repel/attract?
Image 1 will repel because O and O.
Image 2 will attract because O and X.
O= current moving into the screen
X = current popping out of screen
Power =
P = IV
“Pee” is equal to need “IV”
- V = IR
- P = IV
The sum of the voltage variations around a loop is zero is known as what law?
This best describes what type of circuit?
Kirchhoff’s Voltage Law
Series resistance
The resistance in our arterial system are _______.
R1 + R2 + R3 = sum of precapillary arterioles, the only thing providing resistance in the arterial tree.
We have some series circuits in our liver.
Principle of an attenuator (weakener)
What is the potential voltage measured in V2?
What is the potential voltage measured in V3?
20% of V1
80% of V1
If V1 = 10 V and each R = 1 ohm,
What is the total current?
What is the voltage drop across R5?
What is V2 in the first picture?
What is V3?
RT = 5x1ohm = 5ohm
I = V/RT = 10/5 = 2amps
voltage drop across R5 (V2) = 2amps x 1ohm = 2V = 0.2 x 10V
V3 = 2amps x 4ohm = 8V = 0.8 x 10V
The sum of all currents that converge on a node will be zero is known as what law?
Kirchhoff’s Current Law
Rt =
Arterial blood system is an example of what type of system?
DC + AC signal system
Most circulating systems of the body (blood, pulmonary and lymphatic) are connected in ______.
parallel
This ensure that the same force (pressure, voltage) is applied to each of the individual elements (end-organs) or the system.
Physiologic resistance is usually related to the diameter of the conduits through which the “current” (blood, airway gases, etc.) flows. In the arterial blood system, these resistances are controlled by the ______ ______.
precapillary arterioles
The “balance” equation:
V = 0 when R1*R4 = R2* R3 (equal cross products)
Wheatstone Bridge
It is a series and parallel combination of resistances that allows a variation in one of the impedances to alter the “balance” of the circuit.
What type of circuit is analogous to the vascular system?
parallel
If V1 = 10V and each R = 2ohm,
what is the total current?
1/RT = 1/R1 + 1/R2 + 1/R3 = ½ + ½ + ½ =1.5
RT = 1/1.5 = 0.666ohm
I = V/R = 10/0.666 = 15amps
Note: Rt will be less than the smallest resistor.
What is the voltage across A → B?
This bridge is commonly used in _____ ____.
0
pressure transducers
The ratio of the change in an electric charge in a system to the corresponding change in its electric potential.
capacitance or,
physiological “compliance”
The property of a conductor by which a change in current which induces a voltage (electromotive force) in both itself and any nearby via ______’s Law.
inductance
Faraday
Arterial tranducers are barometer or manometer?
manometer, need to zero to atmospheric pressure
Capacitance =
A / d
- increase surface area
- decrease distance to increase capacitance
Parallel capacitance
Ct =
Ct = C1 + C2 + C3 like resistors in series
What type of capacitance is this?
What is Ct?
series capacitance
