TFAS FINAL

In the context of the water metaphor, define voltage

Voltage is the pressure pushing water throrugh a pipe.

In the context of the water metaphor, define current

Current is the flow of water through a pipe.

In the context of the water metaphor, define power

Power is the rate at which the water accomplishes work

In a series circuit, all resistances receive the same

current

In a parallel circuit, divides between paths

Current

When resistances are in parallel, the circuit's equivalent resistance

is lower than the value of each of the individual resistances.

When resistances are in series, the circuit's equivalent resistance

is equal to the sum of the individual resistances.

What can "ground" refer to?

The zero volts reference for voltage measurement.

What can ground refer to?

A structure's physical connection to earth.

What can ground refer to?

The circuit return path between a load and power source.

What can ground refer to?

The safety ground connection in a building's electrical system.

What can ground refer to?

The source to which electricity wants to flow back to.

Where is the circuit breaker located in a typical electrical system?

In the breaker box, on the HOT, attached to each branch circuit.

In the context of the water metaphor, define current.

Current is the flow of water though a pipe.

The potential of ground always _______volts.

0

Why is AC voltage typically measured in volts RMS?

Averaging without RMS gives a value of 0 volts.

Why is AC voltage typically measured in volts RMS?

An AC volts RMS value can accomplish the same amount of work as an equal DC voltage.

What is the purpose of conductor #1? Assume the outlet is wired correctly. (This is a standard electrical outlet)

To provide a 0V reference for connected devices' internal electronics.

Where does a household electrical system acquire its 0V ground reference?

From the center tap of the power company split phase transformer

When resistances are in parallel, the circuit's equivalent resistance _______.

is lower than the value of each of the individual resistances.

Electricity always tries to return to its _______________________.

Source

Regarding transformers, select the statement(s) below that are TRUE. (Select more than one answer, if appropriate.)

Transformers can step up voltage while simultaneously stepping down current.

Regarding transformers, select the statement(s) below that are TRUE. (Select more than one answer, if appropriate.)

Transformers can step up current while simultaneously stepping down voltage.

Regarding transformers, select the statement(s) below that are TRUE. (Select more than one answer, if appropriate.)

Transformers can step up current while simultaneously stepping down voltage.

Regarding transformers, select the statement(s) below that are TRUE. (Select more than one answer, if appropriate.)

When voltage is stepped up, impedance is also raised.

Regarding transformers, select the statement(s) below that are TRUE. (Select more than one answer, if appropriate.)

Transformers allow electrical isolation in a circuit.

What is the current limitation (in amperes) of the typical North American commercial venue/studio circuit breaker? Do not list the units.

20

Identify the potential at the five red numbers.

Potential 1

120V

Identify the potential at the five red numbers.

Potential 2

120V

Identify the potential at the five red numbers.

Potential 3

0-5V

Identify the potential at the five red numbers.

Potential 4

120V

Identify the potential at the five red numbers.

Potential 5

0V

What is the power limitation (in watts) of the typical North American household circuit breaker? Answer numerically. Do not list the units.

1800

In the context of the water metaphor, define resistance.

Resistance is the length and diameter of a water pipe.

What is the current limitation (in amperes) of the typical North American household circuit breaker? Answer numerically. Do not list the units.

15

What is the purpose of the ground rod?

To provide a path to ground in case of a lightning strike or other system surge.

In the context of the water metaphor, define voltage.

Voltage is the pressure pushing water through a pipe.

What is the purpose of the conductors? Assume the outlet is wired correctly. 1

to provide a 0V reference for connected devices' Internal electronic

What is the purpose of the conductors? Assume the outlet is wired correctly. 2

To provide current to connected devices

What is the purpose of the conductors? Assume the outlet is wired correctly. 3

Prevent fire and shock

In a parallel circuit, _______ divides between paths.

Current

Select the proper names for conductors. Assume the outlet is wired correctly. 1

Neutral

Select the proper names for conductors. Assume the outlet is wired correctly. 2

Hot/Live

Select the proper names for conductors. Assume the outlet is wired correctly. 3

Safety ground

Electricity will take all available paths towards toward _______________________.

Ground

From the perspective of audio equipment design, what goals does a safety ground connection accomplish?

Safety grounds provide a low impedance path to the service panel ground in event of a live-to-chassis short.

From the perspective of audio equipment design, what goals does a safety ground connection accomplish?

Safety grounds provide a path to discharge noise on a device's chassis.

What is the proper name of the various XLR pins?

3

Cold

What is the proper name of the various XLR pins?

2

Hot

What is the proper name of the various XLR pins?

1

Shield

What is the power limitation (in watts) of the typical North American commercial business/venue/studio circuit breaker? Answer numerically. Do not list the units.

2400

What is the potential of phantom power on the various XLR pins? 3

+48V

What is the potential of phantom power on the various XLR pins? 1

0V

What is the potential of phantom power on the various XLR pins? 2

+48V

What is the purpose of the conductors? Assume the outlet is wired correctly. (Standard Electrical Outlet) 3

Prevent. Fire and Shock

What is the purpose of the conductors? Assume the outlet is wired correctly. 2

Provide 120 RMS to connected devices

What is the purpose of the conductors? Assume the outlet is wired correctly. 1

Provide a 0V return path

What are the TWO roles of a shield in a three-conductor balanced microphone cable?

Shunt noise to ground

What are the TWO roles of a shield in a three-conductor balanced microphone cable?

Return path for phantom power

Match the patchbay configuration descriptions and names. Mult

Created when multiple front panel jacks wired together, with no break when cables are inserted.

Match the patchbay configuration descriptions and names. Fully Normalled

Signal is routed from outputs to inputs as long. As no plug is inserted to either of the front jacks

Match the patchbay configuration descriptions and names. Half Normalled

Signal is routed from outputs to input as long as no plug is inserted into front input jack

What is the role of each of the XLR pins on a three-conductor balanced audio line? 1

Helps shunt noise to ground and provide a return path for phantom power

What is the role of each of the XLR pins on a three-conductor balanced audio line? 2

Carries audio signal in normal polarity

What is the role of each of the XLR pins on a three-conductor balanced audio line? 3

Carries the audio signal in reversed polarity

In what order is three phase feeder DISCONNECTED from a company switch?

Hot Hot Hot Neutral Ground

What is required to ensure common mode rejection is successful?

A transformer or differential amplifier at the receiving device.

What is required to ensure common mode rejection is successful?

Twisting of the hot and cold lines.

Select the proper names for conductors. Assume the outlet is wired correctly. (Standard Electrical outlet) 3

Safety Ground

Select the proper names for conductors. Assume the outlet is wired correctly. 1

Neutral

Select the proper names for conductors. Assume the outlet is wired correctly. 2

Hot/Live

In the context of the water metaphor, define power.

Power is the rate at which the water accomplishes work.

Electricity will only flow in a complete _______________________.

Circuit

In most situations, which console should provide phantom power?

Monitor

Which description best describes a ground fault circuit interrupter (GFCI)?

GFCIs are safety devices, usually found in electrical outlets, that shut down the circuit in event more or less current is on the hot than neutral.

Isolated ground receptacles feature _______ conductors.

Four (Hot, Neutral, Outlet Safety Ground, Receptacle Chassis Safety Ground)

What is single ended / one legged?

Single ended occurs when either the hot or cold of a balanced line is disconnected and received level drops by -6 dB.

Regarding transformers, select the statement(s) below that are TRUE. (Select more than one answer, if appropriate.)

Transformers allow electrical isolation in a circuit.

Regarding transformers, select the statement(s) below that are TRUE. (Select more than one answer, if appropriate.)

When voltage is stepped up, impedance is also raised.

Regarding transformers, select the statement(s) below that are TRUE. (Select more than one answer, if appropriate.)

Transformers can step up current while simultaneously stepping down voltage.

Regarding transformers, select the statement(s) below that are TRUE. (Select more than one answer, if appropriate.)

Transformers can step up voltage while simultaneously stepping down current.

Identify the potential at the five red numbers.

1

120V RMS

Identify the potential at the five red numbers.

2

120V RMS

Identify the potential at the five red numbers.

3

0-5V

Identify the potential at the five red numbers.

4

120V RMS

Identify the potential at the five red numbers.

5

0V

What are causes of ground loops? (Select multiple answers, if appropriate.)

Differences in impedance between ground connections.

What are causes of ground loops? (Select multiple answers, if appropriate.)

Stray ground voltage, rich in power line noise.

What are causes of ground loops? (Select multiple answers, if appropriate.)

Connection to multiple grounds

Select the phantom power potential for each XLR pin.

Pin 1

0V

Select the phantom power potential for each XLR pin.

2

+48V

Select the phantom power potential for each XLR pin.

3

+48V

Explain a "fully-normalled" patch bay configuration.

Signal is routed from outputs to inputs as long as no plug is inserted to either of the front jacks.

Select the role for each XLR cable conductor.

Hot

Carries the audio signal

Select the role for each XLR cable conductor.

Cold

Carries the audio signal, inverted in polarity

Select the role for each XLR cable conductor.

Sheild

Blocks and Shunts noise to ground, return path for phantom power

Where does a household electrical system acquire its 0V ground reference?

From the center tap of the power company split phase transformer

Which is a more accurate description of how common mode rejection functions?

When a balanced signal enters a device, a differential amplifier or transformer passes the difference in voltage between the two lines. Induced noise is canceled out, as it is the same in voltage between the hot and cold lines.

Select the various situation(s) in which it is SAFE time to use a ground lift cheater plug. (Select more than one answer, if appropriate.)

When 110-120V measures between hot and the outlet screw and the cheater plug's tab is attached to said screw.

A person touches a live 120V power line. What factors determine the severity of the shock? (Select more than one answer, if appropriate.)

The resistance-to-ground of surfaces the person is touching.