S1, W1: Electricity Essentials Current Voltage and Resistance

Electrostatics

the study of stationary electric charges

Electrified

when an object has too few or too many electrons

Electrification

the action of charging something with electricity

electric ground

an object that can always accept electrical charges

Four Electrostatic Laws

1. The electric field points outward from a positive charge and inward to a negative charge

2. Unlike charges attract and like charges repe

3. Electrostatic force is strong when objects are close but rapidly decrease when separated

4. Electrical charges are distributed evenly throughout or on an object except areas of high curvature where they are concentrated

Electrodynamics

the study of electric charges in motion

What kind of energy do electric charges have?

Does a battery have potential energy?

Electric charges have potential energy (electric potential)

• A battery has stored electric charges, which means a battery has stored potential energy

A unit of electric potential

volt (V)

Conductor

material that allows electrons to flow

Insulator

material that prohibit the flow of electrons

Resistance

opposes electron flow (but does not fully inhibit flow)

• measured in Ohms

Semiconductor

material that can serve as a conductor and an insulator

Superconductor

material that exhibits no resistance below a critical temperature

If a conductor is applied to an electric potential, then

electrons (e-) will move along the wire

Current

What units?

Current is the flow of electrons through a conductor

• A unit of current is amperes/amp (A)

Electric power
Units?

work that is being done per second

• Electric power is measured in watts (W)

What are the units for the following

electric potential (V)

current (I)

resistance (R)

Voltage (V) is a unit of electric potential (V)

Amperes (A) is a unit of current (I)

• Amperes can also be (I)

Ohms (Ω) is unit of resistance (R)

Lab flashcards

Dynamic Range

Range of exposure values that our digital detector can capture and create an image off off

• DR can include both optimal and suboptimal exposure values

How does mAs and kVp affect dynamic range?

Insufficient mAs and kVp creates quantum mottle (noise), which is caused by insufficient digital detector exposure = lose radiographic detail

Excessive mAs and kVp creates burnout, which is caused by excessive digital detector exposure = lose radiographic detail

Dose creep

techs taking images on higher end of optimal dynamic range because technology can fix overexposed images.

bad, not ALARA