Electric Charges Quiz

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Questions and Answers

What is meant by the term 'electrical potential'?

The amount of electrical current flowing through a conductor

The total charge of all electrons in an atom

The difference between charged particles at a higher and lower potential (correct)

The number of protons in a neutral atom

Which statement correctly describes the behavior of electrical charges?

Protons repel each other while electrons attract

Charges can be created or destroyed

Like charges attract and opposite charges repel

Like charges repel and opposite charges attract (correct)

Which of the following materials is classified as a conductor?

Adipose tissue

Rubber

Muscle (correct)

Skin

What does the term 'isoelectrical point' refer to?

The balance point where electrical potential is equal between two poles Signup and view all the answers

What characterizes an insulator in terms of electrical current?

It inhibits the passage of electricity Signup and view all the answers

What is the primary unit used to measure electrical power?

Watt Signup and view all the answers

According to Coulomb's Law, what happens between like charges?

They repel each other Signup and view all the answers

Which factor is NOT mentioned as influencing the resistance of a circuit?

Color of the circuit Signup and view all the answers

What is the relationship between temperature and resistance?

Higher temperature leads to less resistance Signup and view all the answers

What measurement unit represents electrical charge?

Coulomb Signup and view all the answers

What is required for electrical current to flow?

A complete uninterrupted path Signup and view all the answers

Which describes the difference between a closed circuit and an open circuit?

A closed circuit has an uninterrupted path, while an open circuit has an incomplete path. Signup and view all the answers

What does the ampere measure?

Rate of current flow Signup and view all the answers

According to Ohm’s Law, how is current related to voltage and resistance?

Current is directly proportional to voltage and inversely proportional to resistance. Signup and view all the answers

What is the unit of resistance in an electrical circuit?

Ohm Signup and view all the answers

What happens to the current if the voltage is increased while resistance remains constant?

The current increases. Signup and view all the answers

Which of the following statements about voltage is TRUE?

Voltage measures the tendency for current flow to occur. Signup and view all the answers

What does the reciprocal of resistance (in ohms) indicate?

Conductance (in mhos) Signup and view all the answers

What is the primary difference between a series circuit and a parallel circuit?

In a series circuit, the current remains the same across all components, while in a parallel circuit, it varies. Signup and view all the answers

Which component of impedance relates to the opposition to the flow of electrical current?

Resistance Signup and view all the answers

How does current density relate to the size of the electrode?

Smaller electrodes lead to greater current density. Signup and view all the answers

What type of circuit is most suitable for sensory-level stimulation?

Series Circuit Signup and view all the answers

In a parallel circuit, how does the electrical flow behave in relation to resistance?

Electrical flow is inversely proportional to resistance. Signup and view all the answers

What characteristic defines inductance in an electrical circuit?

The ability to store electrical energy through an electromagnetic field. Signup and view all the answers

How does the position of pads in a parallel circuit differ from that in a series circuit?

Pads in a parallel circuit are placed at varying distances based on the muscle origin and insertion. Signup and view all the answers

What does an increase in the length of the circuit generally lead to?

Increased resistance. Signup and view all the answers

What is the main difference between direct current (DC) and alternating current (AC)?

DC flows in the same direction continuously. Signup and view all the answers

What is the primary function of a step-up transformer?

It allows high voltage devices to operate from a lower voltage source. Signup and view all the answers

Which of the following best describes the term 'pulse' in electrical waveforms?

A finite period of charged particle movement followed by a period of no current. Signup and view all the answers

Which term describes the intensity of the current and is represented by the height of the wave from the baseline?

Amplitude Signup and view all the answers

How is the frequency of direct current measured?

As pulses per second (pps). Signup and view all the answers

What characterizes a monophasic current?

Uninterrupted unidirectional flow of ions. Signup and view all the answers

In waveform terminology, the term 'phase' refers to which of the following components?

Portion of the wave above or below the baseline. Signup and view all the answers

What does the term 'interpulse interval' specifically refer to?

The period of time between pulses of ion movement. Signup and view all the answers

Which frequency range is considered as low carrier frequency?

0.1 - 1000 Hz Signup and view all the answers

Which of the following statements about factors influencing resistance is false?

Temperature does not have an impact on resistance. Signup and view all the answers

Study Notes

Electrical Charges

Charge is the electrical potential of an atom or ion.
Charge is measured in Coulombs (C).
Electrical potential is the difference between charged particles at a higher and lower potential.
Electrons possess a negative charge and small mass.
Protons possess a positive charge.

Principles of Electrical Charges

There are two types of charges: positive and negative.
Like charges repel, opposite charges attract.
Charge is neither created nor destroyed.
Charges can be transferred from one object to another.

Conductors & Insulators

Conductors transmit electrical current easily.
Examples of conductors include water and muscle.
Insulators prevent or inhibit the passage of electrical current.
Examples of insulators include skin and adipose tissue.
Conductance refers to the ease with which current flows along a conducting medium.

Electricity

Electrical current travels through the path of least resistance.
The cathode is the negative pole with a high electron concentration.
The anode is the positive pole with a low electron concentration.
An imbalance in electrical charge allows the free movement of electrons.
The Isoelectrical Point is the baseline where the electrical potential between two poles is equal, and no electron movement exists.
Electricity flows along a complete pathway between two poles, allowing free movement of electrons from the generating source to the poles.
A closed circuit is a complete, uninterrupted path between two poles.
An open circuit is an incomplete or interrupted path between two poles.

Electrical Current

Electrical Current is the net movement of electrons along a conducting medium.
Current flow is proportional to the magnitude of the force (voltage).
Current always moves from higher to lower potential.
Electrical current requires: a source of electrons, a conductor, and a driving force of electrons (voltage).
Current flow (I) is measured in Amperes.

Ampere

Ampere (A) is the unit of measure that indicates the rate at which electrical current flows.
One Ampere is equal to one Coulomb passing a point in one second.

Voltage

Voltage is the electromotive force or potential difference between two poles.
Voltage measures the tendency for current flow to occur.
Electrons within an electric field position themselves to move to opposite poles, creating the potential for work.
Work is calculated as Force x Distance.
A Volt is the force required to produce movement of electrons, and is a measure of electrical power.

Ohms & Mhos

Ohms (Ω) measure resistance to current flow.
One Ohm is the amount of resistance needed to develop 0.24 calories of heat when 1 Ampere of current is applied for one second.
Mhos are the reciprocal of Ohms.
Conductance is a measure of the ease with which current flows and is the mathematical reciprocal of resistance.

Ohm’s Law

Ohm’s Law states that I = V/R.
Current flow (I) is directly proportional to voltage (V) and inversely proportional to resistance (R).

Electrical Power: Watt

A Watt is a measure of electrical power.
A Watt is the electrical power needed to produce a current flow of 1 Ampere at a pressure of 1 Volt.
Watt = Volts x Amperes.

Coulombs: Electrical Charge

Electrical current flows due to movement of electrons measured in Coulombs (Q).
A Coulomb represents a large number of electrons described as a single unit.
One Coulomb is the charge produced by 6.28 x 10^18 electrons or protons.
Coulomb’s Law explains the relationship between like and unlike charges.

Resistance

Resistance (R) is the opposition to the flow of electrons through a material.
All materials present some degree of opposition to electrical flow.
Skin is the primary biological resistor in electrical current flow.

Factors Influencing Resistance

The material of the circuit influences resistance.
Conductors offer less resistance.
The length of the circuit influences resistance.
Shorter distances offer less resistance.
The cross-sectional area of the circuit influences resistance.
Greater cross-sectional area offers less resistance.
The temperature of the circuit influences resistance.
Higher temperatures generally offer less resistance, although this may not apply to tissue.

Impedance

Impedance is the force resisting the flow of electrons.
Impedance is related to resistance.
It has three components: resistance, inductance, and capacitance.
Resistance is opposition to the flow of electrical current.
Inductance is the ability of a material to store electrical energy through an electromagnetic field.
Capacitance is the ability of a material to store energy by the system.
Inductance and capacitance are related to changes in charged particles and storage of charge within the current, respectively.

Circuit Types

A series circuit has one path for current to pass from one pole to another, often used for sensory-level stimulation.
A parallel circuit has two or more routes for current to pass between two poles, often used for motor-level stimulation.

Series Circuits

Electrons in a series circuit have only one pathway for travel, like connecting a wire between two poles.
The current remains the same in all components along the circuit.
Resistance is equal to the sum of all individual resistors.

Parallel Circuits

Electrons in a parallel circuit have multiple pathways to follow, often choosing the path of least resistance.
Electrons can branch into other parallel or series circuits.
Each path has its own Amperage.
Electrical flow in each path is inversely proportional to the resistance.
Amperage is varied, but voltage remains constant.

Current Density

Current density is the amount of current per unit area.
Physiological effects of electrical stimulation are related to current density.
Current density is inversely proportional to the size of the electrode.
Greater surface area = Less current density.
Less surface area = Greater current density.

Types of Electrical Currents

Direct Current (DC) is a galvanic flow of ions that always flows in the same direction, either positive or negative.
Alternating Current (AC) is current flow that periodically changes its polarity and direction of flow.
Pulsed Current is a unidirectional or bidirectional flow of ions that ceases for a small period of time before the next flow, known as the Interpulse Interval.

Modality Generators

Modality generators shape current wave form, whether AC or DC.
Modality generators create carrier frequency, the frequency of the electrical wave determined by the modality machine.

Carrier Frequency

Low carrier frequency is 0.1 - 1000 Hz, used in most electrical muscle stimulation.
Medium carrier frequency is 1001 - 10,000 Hz, used in Russian stimulation.
High carrier frequency is 10,000 - ⬆ Hz, used in diathermy.

Transformers

Transformers change voltage in alternating current (AC).
Step-up transformers allow a device that requires high voltage to operate from a lower voltage source, common in hand-held modality units.
Step-down transformers allow a device that requires low voltage to operate from a higher voltage source, common in wall modality units.

Waveform Terminology

Amplitude is the intensity of the current, represented by the height of the wave from the baseline.
Frequency is the number of cycles per second.

Phase & Pulse

A phase is a portion of the wave that rises above or below the baseline.
A pulse is a finite period of charged particle movement separated from other pulses with periods of no current flow.
A Pulse consists of one or more phases.

Alternating Current Impulses

Biphasic Current is bidirectional flow of ions with negative and positive phases.
Monophasic Current, also known as Galvanic current, is an uninterrupted unidirectional flow of ions toward a pole.

Phase & Pulse Characteristics

Phase shape refers to the shape of the output current, such as rectangular, triangular, or spike.
Phase charge is the total electrical charge of a single phase, measured in coulombs.
Pulse charge is the amount of electrical charge of a single pulse, calculated as the sum of the phase charges.
A burst is a finite series of pulses flowing for a limited time, followed by no current flow.

Pulse Rate (Frequency)

Waveform repetition at regular intervals is called pulse rate, measured in pulses per second (pps) for direct current and cycles per second (cps) or Hertz (Hz) for alternating current.

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Description

Test your knowledge on the principles of electrical charges, conductors, and insulators. This quiz covers fundamental concepts including the nature of charge, how it is measured, and the behavior of positive and negative charges. Explore the key differences between conductors and insulators in the context of electrical current.