Learning Module A2 Flashcards
What is the simplest circuit connection called?
Series connection
A series connection is the simplest way to connect electrical components for current flow.
How is a series circuit constructed?
By connecting all circuit components in line with one another
A series circuit connects components in a single path for current flow.
What occurs if any part of a series circuit is opened?
Current cannot flow and none of the components will operate
Opening the switch or a component failure can open the circuit.
What happens to electrons in a series circuit connected to a battery?
Electrons leave the negative terminal, flow through the load, and re-enter the positive terminal
This completes the current loop in the circuit.
Fill in the blank: A series circuit provides _______ path for current flow.
one
Only one path is available for current to flow in a series circuit.
True or False: In a series circuit, if one component fails, the entire circuit will stop working.
True
A series circuit is dependent on all components functioning properly.
What establishes a difference in potential in a series circuit?
Current flowing through each resistor
Each resistor offers opposition to current flow, creating a voltage drop.
How is polarity expressed in a circuit?
Relative to another point
Polarity at one point is always compared to another point in the circuit.
What is the total resistance of a series circuit?
The sum of all individual resistances
This is expressed as R_total = R1 + R2 + R3 + …
What happens to the total resistance when individual resistances are connected in series?
They have the same effect as one large combined resistance
Each resistor opposes current flow, contributing to total resistance.
Fill in the blank: The overall resistance in a series circuit is the combined opposition of all the _______.
[in-line resistances]
What are the 2 fundamental laws related in a series circuits?
ohm’s law kerchov’s voltage law
These laws are essential for solving complex circuit problems.
What is the relationship expressed for resistances in a series circuit?
R_total = R1 + R2 + R3 + …
This formula illustrates how to calculate total resistance.
In a series circuit, how does the current behave?
The current is the same at any point in the circuit
This means the total current in a series circuit is equal to the current through any resistance.
What is the formula that expresses the relationship for current in a series circuit?
I_total = I1 = I2 = I3
This indicates that the current is uniform throughout the circuit.
What must exist before any current will flow through a resistance?
A potential difference (voltage)
This is a fundamental principle derived from Ohm’s law.
How is the total voltage in a series circuit determined?
The total voltage is equal to the sum of all individual voltage drops
Voltage drops occur across each resistor as current passes through.
Fill in the blank: As current passes through each resistor in a series circuit, it establishes a difference in potential across each individual resistance, commonly called a _______.
voltage drop
The magnitude of the voltage drop is directly proportional to the value of the resistance.
True or False: In a series circuit, the voltage drop across each resistor is the same.
False
The voltage drop varies depending on the resistance of each component.
What happens to the voltage drop across a resistor in a series circuit when the resistance value increases?
The voltage drop increases as the resistance increases
This is due to Ohm’s law, where E = I x R.
What is the formula that expresses the relationship of voltages in a series circuit?
E_total = E_1 + E_2 + E_3 + …
This formula indicates that the total voltage is the sum of individual voltage drops.
How do you calculate the voltage drop across a resistor using Ohm’s law?
E = I x R
E is the voltage drop, I is the current, and R is the resistance.
True or False: An open in a series circuit interrupts current flow.
True
Without current flow, the voltage drop across each resistor is zero.
What appears across the open if there is no current flow in a series circuit?
The potential difference of the source
A voltmeter connected across the open will read the same as the supply voltage.
What happens when a switch is opened in a series circuit?
The full source voltage appears across the switch contacts
Even though the voltage across the load devices may be zero
When are electrical components generally connected in series?
When it is necessary to:
* Control the amount of current flow in a circuit
* Divide the total voltage of a supply
How are switches utilized in series circuits?
Connected in series with loads to energize or de-energize different loads in power distribution systems
What is the role of protective devices like fuses in series circuits?
They are connected in series with line conductors to protect circuits against higher than normal currents
What is a rheostat?
A variable resistor connected in series with loads to vary the amount of current
Increasing resistance reduces current; decreasing resistance increases current
What is a disadvantage of a series circuit when one device opens?
It interrupts current flow to all remaining devices
What occurs if there is a short in one device in a series circuit?
It causes an increase in current through all the devices
How does changing the resistance value of one device affect a series circuit?
It changes the current, voltage, and power values of all remaining devices
List the three fundamental laws of series circuits.
- R_total = R1 + R2 + R3…
- E_total = E1 + E2 + E3…
- I_total = I1 = I2 = I3…
These laws describe how resistance, voltage, and current behave in series circuits.
How is power defined in the context of series circuits?
Power is the rate of using electrical energy
Power can be calculated using various formulas depending on the known parameters.
What are the three formulas for calculating power in series circuits?
- P = E x I
- P = I^2 x R
- P = E^2/R
These formulas can be used to find power dissipated by individual resistive components or total circuit power.
Fill in the blank: In a series circuit, the total voltage is equal to the sum of the individual _______.
voltages
This is represented by the law E_total = E1 + E2 + E3…
True or False: In a series circuit, the current is the same through all components.
True
This is represented by the law I_total = I1 = I2 = I3…
What does the symbol ‘P’ represent in the context of electrical circuits?
Power
Power is measured in watts (W) and indicates the rate of energy usage.
What is the relationship between voltage drop and resistance in a series circuit?
Voltage drop is directly proportional to resistance
Higher resistance results in a higher voltage drop when the current is constant.
Fill in the blank: The greater the value of a resistor in a series circuit, the ______.
higher the voltage drop
What is the formula for calculating power in a circuit?
P = E × I
Where P is power, E is voltage, and I is current.
What does Kirchhoff’s voltage law state?
Around any closed loop, the algebraic sum of all the voltages is zero
This law is fundamental for analyzing electric circuits.
In Kirchhoff’s voltage law, how are voltage drops considered?
Resistive voltage drops are considered negative quantities
This allows for the source voltage to be considered a positive quantity.
Fill in the blank: Kirchhoff’s voltage law applies to _______ circuits.
closed loop
It is essential for understanding voltage in any closed electrical circuit.
What is the direction of current in Kirchhoff’s law?
From negative to positive through load resistors and from positive to negative in the voltage source.
What is the significance of line resistance in practical applications?
Line resistance may affect circuit performance and needs to be considered, unlike in simple circuit analysis.
Fill in the blank: Line drop is commonly referred to as _______.
the voltage drop across the line conductors.
What is line loss in the context of electrical conductors?
Power loss expressed in watts due to heat energy dissipation as current flows through resistance.
True or False: Line loss calculations are generally significant for determining the efficiency of electrical circuits.
True
What might necessitate the use of larger conductors in electrical applications?
To reduce line drop and maintain load voltage.
What is the effect of connecting voltage sources in series?
Produces a higher voltage value
Commonly used in devices like flashlights and portable transistor radios.
In AC applications, what components are often connected in series?
Generator coils and transformer windings
This is to achieve higher voltage outputs.
What must be observed to obtain a higher voltage output from series-connected sources?
Correct polarity
Individual voltages must act in the same direction.
How are the terminals connected in series aiding configuration?
Negative terminal of one source connects with the positive terminal of the next
Unlike terminals connect to accumulate voltage.
Can individual source voltages in series aiding be of different values?
Yes, as long as they can conduct the same value of current
Generally, they are of equal value.
How is a parallel circuit constructed?
By connecting the terminals of all individual load devices so that the same voltage appears across each component.
Each component receives the same voltage from the source.
What happens to the voltage in a parallel circuit?
The total supply voltage appears across each branch.
This means that each resistor in a parallel circuit receives the same voltage.
How many paths for current flow exist in a parallel circuit?
More than one path.
Each branch provides a separate path for current to flow.
What are the two fundamental characteristics of any parallel circuit?
- The voltage across each branch is the same
- There is more than one path for current to flow through
These characteristics distinguish parallel circuits from series circuits.
True or False: In a parallel circuit, if one branch is opened, current can still flow to the remaining devices.
True
This is a key difference from series circuits.
What happens to the polarity of resistors in a parallel circuit?
The polarity of each of the resistors is the same as the polarity of the source
How is polarity expressed in a circuit?
From one point of a circuit relative to another point with a different electrical potential
What constitutes the total current drawn from the source in a parallel circuit?
The sum of the individual currents through each resistor
According to Ohm’s law, how does current relate to resistance?
Current is inversely proportional to resistance
What effect does adding more resistors in parallel have on total current?
More current is drawn by the circuit
What is the effect of adding resistors in parallel on total circuit resistance?
It reduces the net (total) resistance of the circuit
How do you calculate the current through each resistor in a parallel circuit?
Using Ohm’s law: I = E/R
In a parallel circuit, what value does the total voltage have in relation to the voltage across each branch?
The same value
Fill in the blank: In a parallel circuit, each load resistor acts as an independent _______.
[branch circuit]
True or False: Each branch in a parallel circuit does not see the entire voltage of the supply.
False
What constitutes the total current drawn from the source in a parallel circuit?
The sum of the individual currents through each resistor
What is the effect of adding resistors in parallel on total circuit resistance?
It reduces the net (total) resistance of the circuit
How do you calculate the current through each resistor in a parallel circuit?
Using Ohm’s law: I = E/R
How is the total resistance of a parallel circuit calculated?
Using total circuit voltage and total circuit current
Fill in the blank: In a parallel circuit, each load resistor acts as an independent _______.
[branch circuit]
What happens to the total current as more branches are added in a parallel circuit?
The total current increases
How is the total current in a parallel circuit calculated?
Total current is the sum of the individual branch currents.
What is the formula for total current in a parallel circuit?
I_total = I_1 + I_2 + I_3…
Is the net resistance of a parallel circuit greater or less than any of the individual branch resistance values?
Less than any of the individual branch resistance values.
What is one common method to determine the total resistance of a parallel circuit?
Using the reciprocal equation.
What does Kirchhoff’s current law state?
The sum of the currents entering a junction is equal to the sum of the currents leaving that junction.
True or False: Kirchhoff’s current law is similar to a current conservation law.
True
Fill in the blank: The total outgoing amperage must equal the total _______ amperage at any junction.
incoming
How is the total circuit power (P) represented mathematically?
P = P1 + P2 + P3 + …
What is the primary reason for connecting voltage sources in parallel?
To deliver a current output greater than that of a single source without increasing voltage across a load.
What is the effect of connecting power sources in parallel?
Increases the current capacity.
What is an advantage of parallel-connected power sources?
One source can be removed for maintenance or repairs while maintaining reduced power to the load.
How is the current capacity of parallel batteries calculated?
Equal to that of one battery multiplied by the number of parallel batteries.
What must be true about the terminal voltages of power sources connected in parallel?
They must have the same terminal voltages.
What happens when a lower voltage source is connected to a higher one?
The lower voltage source acts as a load instead of helping share the load current.
What is the correct polarity connection for power sources in parallel?
Like terminals must be connected together: positive-to-positive and negative-to-negative.
Fill in the blank: For parallel batteries, current capacity is equal to that of one battery multiplied by the number of _______.
parallel batteries.
True or False: Parallel-connected power sources can increase both current capacity and voltage output.
False.
What is a combination circuit?
A circuit that combines both series- and parallel-connected elements
1 alternative names for combination circuits?
Series-parallel circuits
How can complex combination circuits be analyzed?
By systematically breaking them down into parallel and series components
What laws can be applied to combination circuits?
The laws that apply to series circuits and parallel circuits separately
Fill in the blank: A combination circuit consists of both _______ and _______ connected devices.
series, parallel
True or False: Combination circuits are commonly encountered in practical electrical applications.
True
