Pretend you are a teacher preparing a quiz for the text I will provide. 
            Each quiz question should follow the format below. 
            Ensure that you carefully recheck the questions and answers for accuracy. 
            The output should be a ready-to-use list of dictionaries for the Python eval function:

            [

                    "question": "WRITE THE QUESTION HERE",
                    "options": ["A) OPTION_1", "B) OPTION_2", "C) OPTION_3", "D) OPTION_4"],
                    "answer": INDEX_OF_CORRECT_ANSWER_IN_OPTIONS_LIST,
                    "explanation": "EXPLAIN WHY THE ANSWER IS CORRECT"

            ]

            Text:
            lectromagnetic radiation (high energy electromagnetic radiation only).

Non-ionizing radiation: radiation associated with insufficient energy to remove electron from an atom (low energy electromagnetic radiation). Example: ultraviolet, infrared, visible light and radio waves. 
Electromagnetic radiation (EMR)
Q: What is the electromagnetic radiation?
A: Electromagnetic radiation Represent:
The motion of pure energy in the form of photons through a space as a combination of both electrical and magnetic fields (waves).
Both field are perpendicular to each other and to the direction of propagation of the photon. 
Photons with shorter wavelength     have higher energy. 
C (velocity of light) = λ (wave length) x f (frequency). 
E (photon energy) = h (planks constant) x f (frequency). 


E    ,   f     ,  λ





Rontgen ray = X-ray:
Discovery of x radiation 
Selective penetration and differential absorption:
X-rays are differentially absorbed by Materials they pass through (they have a selective penetration and absorption power). 
More dense materials like an amalgam restoration will absorb more x-ray (called radioapaque: appear light/white) than less dense materials like skin tissue (called radiolucent: appear dark/black), this characteristic allows us to see images on x-ray film. 
X-ray production
X-rays are produced within the X-ray machine, also known as an X-ray tube. No external radioactive material is involved.
Radiographers can change the current and voltage settings on the X-ray machine in order to manipulate the properties of the X-ray beam produced. 
Different X-ray beam spectra are applied to different body parts. 
X-rays are generated via interactions of the accelerated electrons with electrons of tungsten nuclei within the tube anode. 
There are two types of X-ray generated: characteristic radiation and bremsstrahlung radiation. 
Direct and indirect action of radiation:
In direct action: the free electrons resulting from ionization interact with DNA molecule directly
In in- direct action: the free electrons resulting from ionization interact with water molecules inside the body and creates "free radicals". 

fluid mechanics
Fluid Mechanics (part 1: fluid static)
Density:
Definition: mass Density is the mass m of substances divided by its volume v.
ρ= m/v       [SI unit of mass density Kg/m3 ]
Example 1: (blood as a fraction of body weight)
 The body of man whose weight is 690N contain about 5.2 x 10-3 m3 of blood, (a) find the bloods weight. (b) express it as a percentage of a body weight.
Solution: (density of blood = 1060 Kg/m3) 
Bloods weight   W=mg= (ρv). g= (1060 x 5.2 x 10-3)x 9.8= 54 N
Percentage of bloods weight to the body weight   Percentage% = (54/690)x100= 7.8% 


Pressure:
Definition: Pressure is the force exerted on a surface per unit area.
P=F/A    SI unit is Pascal (1 Pa= 1 N/m2)     , [ in CGS : unit will be dyne/cm2]
Other units:  1atm= 1.013 x105 Pa= 760 mm Hg
                            1 torr = 1 mm Hg.
Example 2: e

            Quiz: