rectifiers, etc.
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
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| Define rectification. | The process of changing alternating current (AC) to pulsating direct current (DC).
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| What are the 2 methods of rectification? | Self rectification; vacuum tube or solid state diode rectification.
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| Which method of rectification is used in mobile radiography? | Self rectification
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| How are rectifying systems connected? | They are connected between the secondary side of the x-ray transformer and the x-ray tube.
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| What is the most commonly used type of semiconductor? | Silicon
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| Define n-type silicon. | Silicon "doped" with arsenic that has an extra electron. (n stands for negative)
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| P-type Silicon | Silicon that contains Gallium and is short of one electron. (P stands for positive)
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| What device is used to test the competency of rectifiers? | Spinning top
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| What is an oscilloscope? | Device used to test the timer in 3-phase, 12-pulse equipment.
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| Why is arsenic called a "donor atom?" | Because it furnishes electrons.
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| Why is gallium called an "acceptor atom?" | Because it can accept electrons.
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| How many valence electrons are in a silicon atom? | 4
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| How many valance electrons are in gallium's outer shell? | 3
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| Silicon makes use of __________ bonding. | Covalent
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| Where is the rectifier located within the x-ray circuit? | Between the secondary side of the x-ray transformer and the x-ray tube.
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| What is the principle disadvantage of self-rectification? | Low heat-loading capacity
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| T/F: With self-rectification, exposure factors (kV and mAs) must be limited to lower values than with full-wave rectification. | True
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| Half-wave rectification is aka ? | One-pulse rectification
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| What is the spinning top used for? | To test the competency of rectifiers with single-phase equipment.
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| Diode | Rectifying semiconductor consisting of a p-type crystal with an n-type to form a p-n junction
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| Thyristor | Silicon-controlled rectifier used for high-speed switching of primary high-voltage x-ray circuit.
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| Thermionic emission | Ejection of electrons from surface of wire due to increased heat, causing an electron cloud
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| Space charge cloud | Same as thermionic emission
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| What is the main advantage of full-wave rectification? | The exposure time for any given technique is cut in half.
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| Which is more efficient for producing x-rays: Single-phase or 3-phase power? | 3-phase
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| Voltage ripple | A way to characterize voltage waveforms.
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| Single-phase power has __% ripple. | 100%
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| 3-phase, 6-pulse power produces __% ripple. | 13 - 25
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| 3-phase, 12-pulse power produces __% ripple. | 4 - 10
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| High-frequency generators have approximately __% ripple | 1%
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| Note: | Less voltage ripple results in higher radiation quantity and quality
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| Oscilloscope | Used to test the timer in 3-phase, 12-pulse equipment.
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| What is the effective kVp with 12-pulse generators? | 95%
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| What is the effective kVp with 6-pulse generators? | 87%
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| Which type of rectification will supply the x-ray tube with the greatest power? | Full wave
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| What is the maximum kVp produced by most 3-phase x-ray generators? | 150
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| To produce equal density and contrast, exposure to the patient with 3-phase equipment is ___ compared to single phase. | Equally
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| To prevent shock, the secondary step-up transformer is __. | grounded
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| Why are 3-phase generators more efficient than single-phase generators? | Voltage never drop to zero.
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| Rectifier | Device allowing current flow in only one direction.
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| Star and delta configurations are related to? | Three-phase transformers
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| With 3-phase equipment, toe voltage across the x-ray tube is __ to __% of the maximum value and is nearly ___ potential. | 87 to 96%, constant
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| What is the percentage of voltage ripple for a single-phase generator? | 100% voltage ripple
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| A full-wave rectified, 3-phase, 6-pulse waveform produces approximately ____% more average photon energy than single phase. | 35
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| A full-wave rectified, 3-phase, 12-pulse waveform produces approximately ___% more average photon energy than single phase. | 40
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| Mobile units operate on _______________ battery-supplied AC current. | Nickel-cadmium
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