physics chapter 4 part 2 Flashcards
Parts of the secondary circuit
Secondary side of step up transformer, the milliamperage meter, a rectifier bank, and the X-ray tube
Parts of the primary circuit
Consists if the main power switch(connected to incoming power supply), circuit breakers, the auto transformer, the timer circuit, and the primary side of the step up transformer
Parts of the filament circuit
Rheostat, step down transformer and the filaments
Know what causes the pulsation in a single phase circuit
The alternating change in voltage from zero to maximum potential 120 times each second in a full wave rectified circuit
Know how a 3 phase circuit or 3 phase power works
Six pulse circuit requires 6 rectifies to produce six usable pulses per cycle, 12 pulse circuit requires 12 rectifies to produce 12 useable pulses per cycle
What does the 3 phase provide?
More efficient xray production
Know what the end result will be for 3 phase
Wave form which never reaches zero, thereby providing an increased voltage
Why circuit breakers are included within a circuit
To protect against short circuits and electric shock
What are auto transformers
An adjustable transformer controlled by the kilovoltage peak selector on the operating console
How does the radiographer control the autotransformer
When radiographer selects a kVp setting
What does the autotransformer operates under?
Principle of self induction
Why is an autotransformer sometimes balled kVp selector
Because of its function
What’s an autotransformers primary purpose
To provide a voltage that will bE increased by the step up transformer to produce the kilovoltage selected at the operating console
What does the step up transformer in the primary circuit change?
◾️increase voltage from autotansformer to kVp necessary for xray production
◾️alternating current from low voltage to high voltage
What is the step up transformer in the primary circuit a dividing line of?
Between the primary and secondary circuits
Where the 2 parts of the step up transformer in the primary circuit are located?
◾️primary coil ➡️ primary circuit
◾️secondary coil➡️secondary circuit
How does the step up transformer differ from the autotansformer
This transformer is not adjustable and increase the voltage from the autotransformer by a fixed amount
Why is the exposure timer located in the primary circuit?
It’s easier to control (turn in or off) a low voltage than a very high one
First variation of timer and explain it
Synchronous timer➡️ based on a synchronous meter
Second variation of timer and explain it
Electronic timer➡️ very sophisticated and accurate timer that is most widely used today based on the time it takes to charge a capacitor.
Third variation of timer and explain it
mAs timer- variation of electronic timer, but it monitors the current passing through the X-ray tube and terminates the exposure when the desired mAs is reached. Located in the secondary circuit.
Know how the aec works differently than an exposure timer
Uses the patient body part of interest as the variable in determining when to terminate exposure. AEC uses a device called the ionization chamber.
What AEC controls
Only the quantity of radiation reaching the IR and therefore has no effect on other image characteristics such as contrast
Know what secondary circuit begins with
The rest of the step up transformer
