Electrical Measurements & Measuring Instruments Multiple Choice Questions on “Autoranging”.
1. Autoranging means __________
a) automatic ranging
b) fixed ranging
c) automobile ranging
d) constant ranging
Answer: a
Clarification: Autoranging refers to obtaining an automatic reading with optimum resolution under all operating conditions. Say for example, 155 mV is displayed as 155.0 and not 0.155.
2. A 3 digit display DVM with a maximum reading of 1999 indicates __________
a) increase by a factor
b) reduction by a factor
c) no change in value
d) depends on the circuit components
Answer: b
Clarification: A 3 digit display DVM with maximum reading capability indicates that any reading above the maximum set limit of 1999 will be reduced by a factor of 10.
3. For a value less than 0200, the instrument should ________
a) read values less than 0200 correctly
b) read values randomly
c) automatically switch range
d) should not respond at all
Answer: c
Clarification: The DVM should automatically switch its range when the display is greater than 1999 units as it is the maximum set limit for achieving a higher sensitivity.
4. ADC counter ________
a) attenuates the signal
b) converts digital to analog
c) converts analog to digital
d) contains information
Answer: d
Clarification: When the count produced by the ADC counter is less than 170, a control pulse is obtained for down ranging. Whereas the control pulse for up ranging is produced once the ADC counter exceeds 1999 units.
5. ADC gives polarity indication.
a) True
b) False
Answer: a
Clarification: ADC contains information required for polarity indication. The polarity of the signal that is integrated is of utmost importance.
6. Integration period is obtained by ________
a) using signal amplitude
b) counting the pulse
c) measuring time
d) by differentiating the signal
Answer: b
Clarification: By counting the pulses we obtain the integration period. Polarity measurement is obtained by making use of the last count or some of the last counts.
7. Integrator’s output is ________
a) attenuated through a filter
b) feedback to the input
c) stored in a flip-flop
d) differentiated
Answer: c
Clarification: The output from the integrator is used to set a polarity flip-flop. The flip-flop’s output is then stored in memory until the next measurement of voltage is obtained.
8. Old information is used to set range relays.
a) True
b) False
Answer: b
Clarification: Range relays are set through the decoder using the new information obtained with the help of a clock pulse. Decimal point is also changed as per the requirement of the new range.
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