# 3 electric physics Flashcards

When direct current is used to power a light bulb, the light bulb
experiences rapid on and off pulses.
A. True B. False

B. False
This is false. The light that is produced through direct current
(battery) will not have short pulses of light but instead will have a
solid glow. The short, on and off pulses of light are due to the
oscillating nature of alternating current.

Removing a resistor within a circuit can act to increase the total
voltage of a circuit.
A. True B. False

B. False
This is false. Total voltage can not be increased within a circuit.
Resistors only decrease voltage, not increase voltage.

The ohm is used to describe:
A. Electrical current B. Flow of current within a
circuit C. Resistance within a circuit D. Electrical
power

C. Resistance within a circuit
The ohm (R) is the base unit used to describe the resistance of
current as it flows through a circuit.

Select the type of current produced by a car battery?
A. Direct current (DC) B. Alternating current
(AC)

A. Direct current (DC)
Batteries use chemical energy to produce direct current. Conversely,
power stations use generators to produce alternating current.

Increasing the flow of current through a circuit is achieved by increasing:
A. Ohms B. Resistance C. Voltage D.
Watts

C. Voltage
As voltage increases, current increases. Voltage is the potential
energy which acts to "push" the electrons through a circuit.
Within a circuit, voltage is provided through either a battery or
other external energy source. While voltage and current are measured
separately, current cannot exist without voltage.

The movement of particles through a conducting material is known as:
A. Voltage B. Watts C. Current D.
Resistance

Current
Current or electrical current is the term used to describe the flow
of electrons through a conducting material. This is the rate of
electron flow. In an x-ray tube, current is measured in milliamperes (mA).

What is the total current (in amperes) of a series circuit with 220
volts and 20 ohms?
A. 240 amperes B. 4,400 amperes C. 11
amperes D. 220 amperes

C. 11 amperes
The total current of a series circuit with 220 volts and 20 ohms is
11 amperes (A). This number can be calculated by dividing 220 volts by
20 ohms.

Current is measured in units of:
A. Ohms B. Volts C. Amperes D.
Watts

. Amperes
The ampere (A) or "amp" is the base unit that describes
the flow of electrons (current) through a conducting material. The
current in an x-ray tube is very small, so it's measured in units of
milli-amperes (mA).

A circuit that contains more than one path for electrons to flow is
described as a:
A. Series circuit B. Closed circuit C.
Parallel circuit D. Open circuit

. Parallel circuit
A parallel circuit, as the name implies, has multiple paths in which
electrons can flow. Parallel circuits are used in virtually all
electronic devices. Parallel circuits are ensure that if one
electrical path breaks down there is another path to continue the
electron flow.

The resistance of electric flow through a circuit is measured in:
A. Volts B. Amperes C. Ohms D.
Joules

C. Ohms
The ohm is the unit of measure used to define the resistance between
two points of a conductor within a circuit.

Total voltage is calculated by multiplying total resistance (ohms) by
total current (A).
A. True B. False

A. True
This is true. When using the Ohm's law triangle, the top of the
triangle is voltage where the right and left sections are resistance
and current (amps). To calculate total volts, you would multiple
resistance with ohms.

Within a circuit, the letter ( I ) is used to represent
A. Voltage B. Resistance C. Current
D. Watts

C. CurrentWithin an electric circuit, the letter ( I ) is used
to represent electric current since current can also be expressed as "intensity".

A connected loop of conducting material is best known as a:
A. Watt B. Circuit C. Transformer
D. Battery

B. Circuit
A circuit is simply a piece of conducting material which allows for
the uninterrupted flow of electrons.

Total current (amperes) is calculated by multiplying total voltage
with total resistance.
A. True B. False

B. False
This is false. Total current is found by DIVIDING total voltage by
total resistance.

Within a parallel circuit, the breaking of a single path will stop
the follow of electricity throughout the entire circuit.
A. True B. False

B. False
This is false. Within a parallel circuit, there can be a break in
one portion of the circuit while still allowing electrical current to
flow. This is not true for a series circuit in which a single break
will stop the flow of electric current.

The flow of electricity within DC power is:
A. Oscillating B. Unidirectional C.
Stationary

B. Unidirectional The flow of electricity within DC power is
known as unidirectional since the electric charge does not switch
between positive and negative. Conversely, AC power rapidly
oscillates from positive to negative.

The rate at which electrons pass through a circuit is described as:
A. Flow B. Voltage C. Current D.
Watts

C. Current
By definition, current is the rate at which electrons flow through a
circuit. In an x-ray circuit, current is measured in milliamperes
(mA). An increase in electron flow results in an increase in current.

What is the total voltage of a parallel circuit if the circuit has a
current of 20 A and resistance of 5 ohms?
A. 4 V B. 100 V C. 0.25 V

100 V
Using the Ohm's triangle, place 20 A on one bottom side and 5 R on
the other bottom side. Multiply both sides to calculate the total
volts. 20 A x 5 R = 100 V.

Homes in the United States typically receive alternating current (AC)
with a frequency of:
A. 110 Hz B. 210 Hz C. 60 Hz D. 20
Hz

. 60 Hz
The standard AC frequency in the US is 60 Hz. This is the rate at
which the electrical charge alternates between negative and positive.
60 Hz is equal to 60 times per second.

What type of current must be used in the x-ray tube of the x-ray circuit?
A. Alternating current (AC) B. Direct current
(DC)

B. Direct current (DC)
Direct current (DC) is used for the operation of the x-ray tube.
This is necessary to ensure that electrons flow in only one direction
through the x-ry tube (cathode to anode). Since power to the x-ray
machine is initially provided as alternating current (AC), the x-ray
machine must convert the AC power into DC.

The degree of resistance provided by an individual resistor within a
circuit is measured in:
A. Volts B. Watts C. Ohms D.
Amperes

C. Ohms
The ohm is the unit of measurement used by resistors. A resistor is
used to decrease the flow of electric current through a circuit.

The charge of an electron is:
A. Positive B. Negative C. Neutral

Negative
Electrons have a negative charge. This is true at all times,
regardless where the electron is located.

What is the voltage of a parallel circuit with a total resistance of
5 ohms and total current of 0.5 amps?
A. 10 V B. 5.5 V C. 2.5 V

C. 2.5 V
The voltage is calculated by multiplying 0.5 x 5 = 2.5 V.

Within the Ohm's triangle, resistance is discovered by _____________
volts with amps.
A. Multiplying B. Dividing C. Adding
D. Squaring

B. Dividing
Dividing the top portion (volts) with resistance (ohms) will provide
for the total current (amps).

The ability of a system to do work is best know as:
A. Voltage B. Watts C. Energy D.
Current

. Energy
Energy is the quantitative property that must be transferred to an
object in order for there to be work. Energy can be described as the
power derived from a physical or chemical resource.

What is the total resistance of a parallel circuit with three
resistors of 6 ohm, 12 ohm, and 2 ohm?
A. 20 ohms B. 12 ohms C. 1.3 ohms

C. 1.3 ohms
Total resistance within a parallel circuit is found by adding the
fractions 1/6 + 1/12 + 1/2 and then cross multiplying. NOTE* this
process is shown in detail within the video parallel circuit video.

What type of current is found within home electrical outlets?
A. Direct current (DC) B. Alternating current
(AC)

. Alternating current (AC)
All residential homes and businesses in the US are powered by
alternating current (AC). Alternating current (AC) is produced at
power plants by the spinning of the positive and negative charged cylinders.

Within the Ohm's triangle, total voltage is found by _____________
ohms with ampers.
A. Adding B. Dividing C. Multiplying
D. Squaring

C. Multiplying
Multiplying Ohms (resistance) with current (amps) provides the total voltage.

A circuit with a single path for electric current flow is defined as a(n):
A. Parallel circuit B. Closed circuit C.
Series circuit D. Open circuit

C. Series circuit
A series circuit is defined as having a single path in where
electrical current can flow. Within a series circuit, any break within
the circuit will cause electrical current to stop.

Electrical resistance, measured in Ohms, is sometimes represented by
the letter:
A. I B. A C. O D. R

. R
(R) is most attributed to Ohms since Ohms is expressed as resistance.

Within a series circuit, total resistance can be calculated by:
A. Multiplying the ohms of all resistors within the
circuit B. Summing the ohms of all resistors within the
circuit C. Subtracting the ohms of all resistors within the
circuit

B. Summing the ohms of all resistors within the circuit Within
a series circuit, adding together (summing) the ohm values of each
resistor will provide the total resistance value.

An increase in electrical potential will produce an increase in:
A. Watts B. Charge C. Voltage D.
Current

C. Voltage
An increase in electrical potential between two particles produces a
greater voltage. Voltage, or "electric potential", is
defined as the unit of potential energy per unit charge.

Conduction of electrical current requires which of the following?
A. Parallel circuit B. Voltage C.
Resistance

Voltage
The movement of electrons through a conducting material is made
possible by the addition of a potential difference, called voltage.
Voltage can be thought of as the "power" to push the
electrons through a conduction material.

In the United States, most radiologic equipment must receive a
minimum incoming voltage of:
A. 1000 V B. 110 V C. 210 V D. 220
V

D. 220 V
220 V is the standard voltage needed to efficiently power most US
radiologic equipment. This is twice the standard voltage used in
personal residences (110 V).

Electrical current is measured in units of:
A. Watts B. Volts C. Amperes D.
Ohms

C. Amperes
Electrical current is measured in amperes (A). In an x-ray tube, the
current is very small, so the current is measured in mili-amperes (mA).

Select the term that describes a device used to store energy.
A. Circuit B. Battery C. Conductor
D. Insulator

. Battery
A battery is a device through which chemical energy is converted
into electricity and used as a source of power.

An outward projecting electric field is produced from this type of
charged particle.
A. Positive B. Negative C. Netural
D. Opposite

A. Positive
Positively charged particles have an electric field that radiates
outward. Conversely, negatively charged particles have an electrical
field that radiates inward.