RC Exam - Elec 15
In a class A amplifier, the collector current, Ic, flows for: 120° or less of the ac input cycle. 180° of the ac input cycle. 360° of the ac input cycle. 90° of the ac input cycle.
360° of the ac input cycle.
The potential divider method of biasing is used in transistor amplifier to make the operating point: Going to base value Act as ground Almost independent of β Almost independent of β
Almost independent of β
Conduction electrons have more mobility than holes because they: Decrease the number of charged carriers Change the chemical properties of semi conductivity Make semiconductors less than 100% pure Alter the crystal structure of the pure semiconductor
Alter the crystal structure of the pure semiconductor
Doping materials are called impurities because they: Alter the crystal structure of the pure semiconductor Make semiconductors less than 100% pure Change the chemical properties of semiconductors Decrease the number of charging carriers,
Alter the crystal structure of the pure semiconductor
Major parts of the current in an intrinsic semiconductor are due to: Holes in the valence band Thermally generated electrons Conduction-band electrons Valence-band electrons
Conduction-band electrons
The Q-point in a voltage amplifier must be in the middle of the active region to give: Stable operation point Small input dc voltage Distortionless output Less number of resistor
Distortionless output
The main current crossing the collector current in a normally biased NPN- transistor is: Hole current Drift current Equal to the base current Diffusion current
Drift current
The emitter of a transistor is generally doped the heaviest because it: Has to supply the charge carrier Must possess low resistance Has to dissipate maximum power Is the first region of the transistor
Has to dissipate maximum power
In a 5 V level detector circuit, the: Input signal must be riding on a +5 V Output is limited to 5 V Inverting input is connected to +5 V Input signal is limited to a 5 V peak value
Inverting input is connected to +5 V
In a semiconductor diode, the barrier potential offers opposition only to: Minority carriers in both regions Holes in the P-region Majority carriers in both regions Free electrons in N-region
Majority carriers in both regions
A thermistor can be used in a constant-current configuration or a Wheatstone bridge can measure a greater temperature range than a thermocouple All of the choices is less sensitive than an RTD
can be used in a constant-current configuration or a Wheatstone bridge
The feedback path of an ideal op-amp integrator consists of a: resistor and capacitor in series resonant circuit resistor capacitor
capacitor
Instrumentation amplifiers are used primarily in: test instruments amplitude modulators high-noise environment filter circuit
high-noise environment
In a scaling adder, the: ratio Rf/R must be the same for each input input resistors are all the same value input resistors have values that depend on the assigned weight of each input feedback resistor is equal to the average of the input resistor
input resistors have values that depend on the assigned weight of each input
The three parts of basic isolation amplifiers are connected by: input, output and power input, output and coupling amplifier, filter and power gain, attenuation and offset
input, output and power
A higher gauge factor indicates that the strain gauge is: has more total resistance more sensitive to a change in length made of a physically larger conductor less sensitive to a change in length
more sensitive to a change in length
The op-amp comparator circuit uses: regenerative feedback no feedback positive feedback negative feedback
no feedback
One characteristic of a voltage-follower is ____. A_cl > 1 noninversion inversion high R_out
noninversion
An active limiter with back-to-back zener diodes across the feedback paths limits the: positive peaks only negative peaks only positive peak to the zener voltage and the negative peak to -0.7 V positive and negative peaks
positive and negative peaks
The purpose of a comparator is to: maintain a constant output voltage changes produce a change in output when an input voltage equals a reference voltage detect the occurrence of a changing input voltage amplify an input voltage
produce a change in output when an input voltage equals a reference voltage
Typically, an instrumentation amplifier has an external resistor used for: establishing the input impedance interfacing with the instrument setting the current gain setting the voltage gain
setting the voltage gain
Many types of pressure transducers are made with: None of the choices RTDs thermistors strain gauges
strain gauges
The purpose of a 3-wire bridge is to eliminate: nonlinearity of an RTD the effects of wire resistance in an RTD circuit None of the choices noise from the RTD resistance
the effects of wire resistance in an RTD circuit
To convert a summing amplifier to an averaging amplifier, the ratio Rf/R must equal the number of inputs answers all input resistors must be a different value and the ratio Rf /R must equal to the reciprocal of the number of inputs all input resistors must be a different value the ratio Rf /R must equal to the reciprocal of the number of inputs
the ratio Rf /R must equal to the reciprocal of the number of inputs
A feedback attenuation of a voltage-follower is _____. greater than unity less than unity variable unity
unity
