Electrical Theory 1: Direct Current Final review

This is a compilation of 2024 year CML quizzes over Lessons 1-7.

EIR

Voltage = Current * Resistance

PIE

Power = Current * Voltage

Power is Measured in what?

Watts

Voltage is measured in what?

Volts

Current is measured in what?

Amps

Resistance is measured in what?

Ohms

Electricity is the movement of what?

Electrons

Conventional current flows electrons flow from which end of the terminals?

Positive to negative

The atom is best described as?

The simplest form of matter

Potential differences occurs when?

There are more electrons on one side of the terminal than the other

What additional requirements must test instrument manufacturers follow?

Application requirements, NFPA 70E, and OSHA

What are valence electrons?

Electrons that are in the outermost shell

How to get total resistance in a series circuit?

Add all of the component resistances together R = E/I

How to you get total current in a series circuit?

Current is the same through all components. I = E/R

How do you get total voltage in a series circuit?

Add all the voltages of the components together. E = I*R

What are the two general types of resistors?

Fixed and Variable

What is a variable resistor?

A moveable contact that is adjusted by turning a shaft or stem

What are some tips of specific resistors?

Composite Carbon, Metal Film, Metal Glaze, Wire Wound

What are types of circuit drawings?

Schematic and pictorial

What is a series circuit?

A circuit that only has one path for current to flow

What is a parallel circuit?

A circuit where the current has two or more paths for current to flow and each branch is less than the total current in the circuit

How to find resistance in a parallel circuit

1/( (1st) r^-1 + (2nd)r^-2 + ETC). R = E/I

How to find voltage in a parallel circuit?

Voltage is the same in a parallel circuit. E = I * R

How to find current in a parallel circuit?

Add all of the currents together to get the total. I = E/R

The whole what is dropped across each load in a parallel circuit and therefore the same?

Applied voltage

After having the total resistance and applied voltage in a circuit, what is the next logical step?

Find the total current flow

Equivalent Resistance is when you do what to a series branch?

When you convert a parallel circuit into a series circuit

When solving your combination circuits, the what can be found using Ohm’s law because the what for that group is the same when they are in parallel?

component current and component voltage

Is the current the same in components that are in series-parallel?

yes

What is a combination circuit?

A circuit where there are both series and parallel branches

The formula E (subset 1) = Et = * ((R (subset 1))/Rt)

The law of Proportionality

What needs to be found for each inductor when using super position?

Power source

a. Repeat this procedure for each power source in the circuit; determine the amount of the current and the direction of the current flow through the load.
b. Assume a direction of current flow through the load.
c. Select one power source and replace all the other power sources in the circuit with a short circuit.
d. Calculate the current flow for the selected source.

C, B, D, A

Which theorem states that any source can be reduced to an equivalent current source and an equivalent resistance?

Norton’s

According to the Laws of Proportionality, if a resistor in a parallel circuit has twice the resistance of a second resistor, it will have   ?   the current of the second resistor.

1/2

Kirchhoff's Voltage Law states that algebraic sum of

the voltage drops around any closed path or loop is 0

Which Theorem states that any source can be reduced to a single equivalent voltage and an equivalent resistance in series.

Thevenin’s

The voltage across any load is   ?   to the value of the resistance of that load in a series circuit.

Directly Proportional

In a parallel circuit, the current through each resistor is   ?   to its resistance.

Inversely proportional

When current flows to the intended destination through the load and back to the source, it is said to be   ?  .

Complete

Lamps will have ratings for both   ?   and   ?  .

Voltage and Power

When current does not flow in a circuit, it is called a(n)   ?   circuit.

Open

When controlling a load from three locations, a   ?   is used in conjunction with two   ?  .

4 way / 3 way switches

American Wire Gauge (AWG) sets the standards of sizes in the United States for   ?  .

conductors

When current returns to the source without flowing through the load, it is referred to as a(n)   ?  .

Short

Circular mils are the units used to measure the   ?  .

the cross sectional area of an American conductor

A switch that either makes or breaks one circuit path at a time is referred to as a   ?  switch.

single pole

A lamp with higher resistance will cause the wattage of the lamp to   ?  .

be lower

What is the formula for calculating the resistance of wire or conductor?

R = (K * L)/A

Three way switches control lighting from how many locations?

2

A switch is a   ?  .

mechanical device designed to allow or interrupt the current flow in a circuit

Which two values are included on normal switch ratings?

Maximum current and voltage

Relative motion between the   ?   and   ?   is needed to have a voltage induced.

conductor and magnetic fields

Increasing the number of loops in a coil will increase the   ?   of the magnetic field.

strength

The   ?   poles of magnets attract while   ?   poles repel.

unlike and like

The flux lines of a magnet leave the   ?   pole and enter the   ?   pole.

north and south

Electromagnetic fields are formed by combining   ?   and   ?  .

electrostatic field and magnetic fields

If the direction of the current flow changes, what else will change?

The direction of the conductor passing through the flux lines

When current flows through a conductor, it develops a magnetic field of concentric circles expanding   ?   and outward from the conductor.

perpendicularly

When applying the Left-Hand Rule for Conductors, one imagines holding a conductor in the left hand and pointing the thumb in the direction of current flow. The encircling fingers will give the direction of the   ?  .

magnetic field

Increasing the   ?   of the wire that cuts a magnetic field will also increase the magnitude of the voltage produced by electromagnetic induction.

number of loops

A DC generator creates a current that   ?   and an AC generator creates a current that   ?  .

flows in one direction / flows in two directions

Ferromagnetic materials are materials that   ?  .

are easily magnetized

Wrapping the windings of a conductor closer together creates a   ?   magnetic field.

stronger

In AC generators,   ?   are used instead of a commutator.

slip rings

The opposition to the passage of flux lines is called   ?  .

reluctance

In DC Theory, what does the Left-Hand Rule for generators show?

The motion, direction of magnetic field, and the direction of the current flow for electromagnetic induction

Using the Left-Hand Rule for generators, the   ?   indicates the direction of the current induced into the armature.

middle finger

The magnetic lines of force flowing into and out of magnets cause magnets held close to each other to have   ?  .

attraction or repulsion

A voltage would be induced if there was a motion of electrons in a conductor caused by an interaction between the   ?   and   ?  .

magnetic field of the magnet / magnetic field of the electrons

If the direction of the current flow in a conductor is known, what can be determined by using the Left-Hand Rule for Conductors?

direction of flux lines

Increasing the   ?   conductor will increase the strength of the electromagnetic field around that conductor.

currently flowing through