DC Theory All Lessons

Flash Cards from Lesson One Quiz

Regarding units of measurement, ? is to electrical potential as ? is to electrical current.

a. volt / amp

b. watt / volt

c. watt / amp

d. volt / watt

A. volt / amp

How much power is consumed in a circuit when the current is 6 amps and the voltage is 55 volts?

330 Watts P(Power)=E(Voltage) x I(Current

Facility procedures and manufacturer requirements must always be followed when using test instruments; in addition, ? must also be followed. (Select all that apply)

a. application requirements

b. NFPA 70E

c. OSHA

d. the NEC

A / B / C

When using Ohm's Law to solve for the value of E, I is to be ? R.

Multiplied

? is what is consumed, or converted, when a voltage is applied to a circuit and current flows through a load.

a. Current

b. Power

c. Resistance

d. Voltage

B. Power

What would the total current in a circuit be if the applied voltage is 80 volts and the resistance is 20 ohms?

4 Amps I(Amps)=E(Voltage)/R(Resistance)

Which electrical formula should be used to find the maximum current that can be carried by a resistor if the resistor's resistance and wattage rating are known?

I(Amps) = Squareroot of P(Watts) / R(Ohms)

What is the formula which defines the voltage drop across a load in an electrical circuit?

E(N) = I(T) × R(N)

When electrical current is shown as flowing from the positive terminal of the source, through the load(s), and back to the negative terminal of the source, this type of current flow is referred to as ? current flow.

a. alternating

b. conventional

c. electron

d. variable

B. Conventional

Other terms that are often used interchangeably with the term potential difference are voltage and ? .

a. current

b. electrolysis

c. electromotive force

d. electron flow

C. electromotive force

The variable letter "R" in Ohm's Law stands for ? , and is measured in ? .

resistance / ohms

Determine how much power is consumed in a circuit when the resistance is 30 ohms and the applied voltage is 60 volts.

120 Watts. P(Power)=E(Voltage)^2/R(Resistance)

The value 200,000 ohms can also be expressed as ? .

200 kΩ (kΩ move the decimal point to the left 3 spots)

How much power is consumed in a circuit when the resistance is 30 ohms and the applied voltage is 56 volts? (Round the final answer to one decimal place.)

104.5 Watts

What would the total voltage in a circuit be if the current is 8 amps and the resistance is 30 ohms?

240 Volts E(Volts) =I(Amps)xR(Ohms)

Determine the total resistance in a circuit where the power dissipated is 25 watts and the supplied voltage is 50 volts.

100 Ohms R(Ohms)=E(Volts)^2/P(Watts)

The water that is flowing through a pipe can be thought of as, and analogous to, electric ? .

Current

If the voltage is increased in a circuit and all other components remain the same, the power consumed in the circuit will ? .

Increase (More voltage more shock)

In an atom, ? have a positive charge, ? have a negative charge, and ? have no charge.

protons / electrons / neutrons

The unit of measurement for ? is the amp

The unit of measurement for ? is the ohm

The unit of measurement for ? is the volt

The unit of measurement for ? is the watt

Electric Current

The Opposition to Current Flow

Electrical Potential

Electrical Power

The ohm is the unit of measure for ? .

Resistance

Determine how much power is consumed in a circuit when the current is 10 amps and the applied voltage is 23 volts.

230 Watts P(Power)=E(Volts)xI(Amps)

The symbol for the ohm is ? .

Ω - Horseshoe

According to Watt's Law, the total power consumed by a circuit is equal to E(T) ? , or the sum of the power consumed by each resistor.

Multiplied by I(T)

The value 40 watts can also be expressed as ? .

0.04 kW (Kilo=moves decimal to the left 3 spaces)

The variable letter "E" in Ohm's Law stands for ? , and is measured in ? .

electromotive force / volts

Flash Cards from Lesson Two Quiz

In a ? circuit, the current measured anywhere in the circuit is the same as the current measured in the supply and return path from the load(s).

Series

A variable resistor is best defined as a resistor with ? .

Select one:

a. a constant resistance regardless of changes in voltage or temperature

b. a fixed value

c. a moveable contact that is adjusted by turning a shaft or stem

d. the ability to hold magnetism after the magnetizing force is removed

C. a moveable contact that is adjusted by turning a shaft or stem

Which of the following is/are fixed resistor types mentioned in the training? (Select all that apply.)

Select one or more:

a. Composition carbon

b. Metal film

c. Metal glaze

d. Silicon

e. Wire wound

a. Composition carbon

b. Metal film

c. Metal glaze

e. Wire wound

The equation IT = I1 = I2 = I3 = ⋯ I(N) solves for total ? in a series circuit.

I = Current (Doesn't change)

The equation ET = E1 + E2 + E3 + ... E(N) solves for total ? in a series circuit.

E = Voltage (ET is all Voltage added up)

Determine the value of the resistor, R1, given: ET = 138 V, E1 = 6 V, E3 = 26 V, and R2 = 245 Ω

R1 = 13.9 ohms

When resistors are connected in series, the voltage drops across each resistor are ? to find the total circuit voltage.

Added

One way to calculate the total power in a series circuit is to ? the component wattages.

Add

When resistors are connected in series, their values are ? to find the total circuit resistance.

Added

This ? or ? drawing shows components of a circuit as they would actually appear.

a. architectural / component

b. photographic / pictorial

c. pictorial / architectural

d. pictorial / component

D. pictorial / component

If the total resistance of the circuit is 129 ohms, determine the value of R1, given:RT = 129 Ω, R2 = 32 Ω, R3 = 13 Ω, and R4 = 24 Ω

RT-R2-R3-R4=R1 (60 ohms)

In order for a circuit diagram to be easily understood across different languages and cultures, most electricians prefer a(n) ? drawing.

a. architectural

b.component

c.pictorial

d. schematic

D. schematic

A circuit where there is only one path for current to flow is called a ? circuit.

Series Circuit

The equation RT = R1 + R2 + R3 + ... R(N) solves for total ? in a series circuit.

Resistance

Determine the value of the resistor, R1, given: ET = 185 V, E1 = 21 V, E3 = 34 V, and R2 = 450 Ω

72.2 ohms

The sum of the power dissipated by each resistor in a series circuit is equal to the ? .

a. total current in the series branch

b. total power

c. total resistance

d. voltage times the resistance

B. Total Power

Determine the total current, IT, for the circuit, given:

ET = 184 V, E1 = 26 V, E3 = 26 V, and R2 = 422 Ω

(Round the FINAL answer to two decimal places.)

.31 Amps

? and ? are the two general types of resistors.

a. Conductor / variable

b. Fixed / conductor

c. Fixed / variable

d.Variable / adjustable

C. Fixed / variable

Which of the following is a basic rule that applies to a series circuit? (Select all that apply.)

Select one or more:

a. The current is the same wherever it is measured in the circuit.

b. The total current is added for each circuit component.

c. The total power is the sum of the individual circuit watt dissipations.

d. The total resistance of the circuit is the sum of all the individual resistor values.

e. The total voltage of the circuit is the sum of all the component voltage values in the circuit.

a. The current is the same wherever it is measured in the circuit.

c. The total power is the sum of the individual circuit watt dissipations.

d. The total resistance of the circuit is the sum of all the individual resistor values.

e. The total voltage of the circuit is the sum of all the component voltage values in the circuit.

Flash Cards from Lesson Three Quiz - Parallel

Determine the total resistance of this circuit, given: ET = 90 V, R1 = 9 Ω, R2 = 36 Ω

7.2 Ohms

Determine the voltage across resistor R2, given: R1 = 49 Ω, R2 = 81 Ω, and I1 = 3.5 A

The total current in a parallel circuit is the ? the component currents.

sum of (Current is I or Amps)

Determine the total resistance of the circuit, given: R1 = 177 Ω, R2 = 181 Ω, and R3 = 190 Ω

60.84 Ohms

The voltage applied to each load in a parallel circuit is ? the total voltage.

Equals to (Voltage is E or Volts)

A parallel circuit has multiple paths for ? to flow.

Current (I or AMPS)

The current that leaves and re-enters a single power source in a parallel circuit is called the ? .

Total current

Select the formula to find total current in a parallel circuit when the total resistance and total voltage are known.

IT = ET / RT

Three loads of varying wattages are connected on a circuit. Which formula would you use to determine the total power consumed by the circuit when all loads are operating?

PT = P1 + P2 + P3

Determine how much power would be consumed in a parallel circuit that has a source voltage of 290 volts and a total circuit current of 4.3 amps.

1247 Watts

The "Assumed Voltage" formula is used when the ? is not known and can be used to solve for the actual resistance total of the circuit.

Source or Branch Voltage

Determine the current flowing through R2, given:R1 = 8 Ω, R2 = 7 Ω, and I1 = 4 A

4.6 Amps

Which statement about parallel circuits is correct? (Select all that apply.)

a. Circuit components that are connected in such a way to provide a single current path through each component are said to be connected in parallel.

b. For a circuit to be considered a parallel circuit, there must be at least two paths for the current to flow.

c. Parallel circuits must contain more than one voltage source.

d. The current through any branch of a parallel circuit will be less than the total circuit current.

b. For a circuit to be considered a parallel circuit, there must be at least two paths for the current to flow.

d. The current through any branch of a parallel circuit will be less than the total circuit current.

The formula IT = I1 + I2 + I3 + ⋯ IN is used for finding ? in a parallel circuit when ? is/are known.

total current / component currents

Determine the current flowing through R2, given:R1 = 3 Ω, R2 = 5 Ω, and I1 = 13 A

7.8 Amps

Determine the voltage of the source if each resistor has a resistance of 157 Ω and the total current is 6 amps.

471 Volts

Adding parallel loads to a circuit will ? total circuit resistance and ? the total circuit current.

decrease / increase

Determine the total resistance of the circuit, given:R1 = 177 Ω, R2 = 106 Ω, and R3 = 145 Ω

45.50 Ohms