Electricity Flashcards by Cindy Ehret

Conventional current is the movement of _____ charges.

positive

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Identify the following symbols:

alternating current
battery
amplifier
amplifier 2
capacitor
capacitor 2
resistor
resistor 2

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Identify the following symbols:

inductor
transformer
circuit breaker
fuse about to blow
ground
ground 2
diode
meter
transistor
rectifier
wire

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Identify the following circuits:

open circuit

closed circuit

short circuit

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What is defined as the “flow of charges per unit time”?

current

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What does the symbol with “A”? represent?

ammeter

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Definition: potential difference which is the potential energy required to move a charge of one coulomb from point A to point B.

voltage

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What does the symbol with “V” indicate?

volt meter

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V = IR is known as what law?

Ohm’s Law

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Pressure (P) of voltage units:

dynes/cm²

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Flow of current units:

cm³/sec

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Heat flow (q) unit

Watts

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Solute concentration units?

Solute flow units?

mg/ml

mg/min

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The corollary to Ohm’s law is known as _____ law.

Ohm’s Law: V = IR

Darcy’s Law: P = QR

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What type of current varies around zero?

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What depiction most represents the cardiovascular system?

DC + AC shows varying around a mean pressure

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This waveform depicts what?

arterial blood pressure waveform

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How is the mean pressure or the arterial pressure obtained?

Calculated as the area under the curve.

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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?

R_T = 5x1ohm = 5ohm I = V/R_T = 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

R_t =

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