An XY recorder plots the instantaneous relation between two variables. It records one quantity with respect to another quantity.
The writing pen will be deflected in both the X direction and the Y direction on a stationary chart paper. Depending on the desired application one or more write pens are used.
XY recorders are employed using proper transducers for recording physical quantities as a function of other physical quantities.
12. High-value potentiometer resistance leads to _____.
Low sensitivity
High sensitivity
Low non-linearity
Less error
Answer.2. High sensitivity
Explanation:
In a potentiometer, resistance is directly proportional to the length of the wire. High-value resistance leads higher length of wire which leads to a higher sensitivity of the potentiometer (pot).
13. _______ potentiometer is used for large currents at high temperature.
Non-wire Potentiometer
Wire wound Potentiometer
Both 1 and 2
None of the above
Answer.2. Wire wound Potentiometer
Explanation:
The wire-wound potentiometer is used for large currents at high temperatures. The materials used for wire-wound potentiometer are platinum, nickel-chromium, nickel-copper, or any other precious resistive element.
The resolution of the wire-wound potentiometer is about 0.025 to 1 0.05 mm. The resolution is limited by the number of turns accommodated.
The disadvantage of wire wound potentiometer is that its usage is limited to the high frequency only, because of capacitances between windings and shaft, two turns of the winding, etc.
14. A 3-turn 100 kΩ potentiometer with 1% linearity uses 30 V supply. What is the potentiometer constant?
0.1 V/turn
10 V/turn
33.33 V/turn
0.3 V/turn
Answer.2. 10 V/turn
Explanation:
The linearity of the potentiometer gives the relationship between the position of resistance and the potentiometer i.e. if the knob of the potentiometer is at the middle position then the output voltage is half of the voltage through it.
Now, the potentiometer constant ‘k’
K = E/N
Where E = supply voltage
N = turn
Now,
K = 30/3
K = 10 V/turn
15. Which of the following devices should be used for accurate measurement of low D.C. voltage?
Small range moving coil voltmeter
D.C. potentiometer
Small range thermocouple voltmeter
Hotwire voltmeter
Answer.2. D.C. potentiometer
Explanation:
D.C. potentiometer is used for accurate measurement of low D.C. voltage because the result obtained does not depend upon the actual deflection of a pointer
A potentiometer is an instrument designed to measure an unknown voltage by comparing it with a known voltage
Measurement using the comparison method is capable of a high degree of accuracy
A potentiometer is extensively used for the calibration of voltmeters and ammeters
16. A Murray loop test is conducted on a 400-m long faulty cable. At balance, the resistance connected to the faulty core was set to 40 Ω and the resistance of the resistor connected to the sound core was 60 Ω. What is the distance of the fault from the test end?
267 m
217 m
160 m
320 m
Answer.4. 320m
Explanation:
Given R2 = 40 ohm R1 = 60 ohm
In Murray Loop test the length of the faulty section is given as
17. The open circuit EMF of the Weston standard cell used for standardization of potentiometer is:
1.0183 V
1.183 V
1.1 V
1.0 V
Answer.1. 1.0183 V
Explanation:
The Weston cell is a wet-chemical cell that produces a highly stable voltage suitable as a laboratory standard for calibration of voltmeters.
The internal resistance of a standard Weston cell is of the order of a fraction of an ohm.
The open-circuit EMF of the Weston standard cell used for the standardization of the potentiometer is 1.0183 V.
18. Current in a circuit is measured using a simple slide wire. What will be the Voltage drop per unit length if the standard cell is of emf 2.38 V balanced at the length of 35 cm?
0.68 V/cm
0.068 V/cm
68 V/cm
6.8 V/cm
Answer.2. 0.068 V/cm
Explanation:
Given,
V = 2.38 volts
l = 35 cm
The potential difference (or fall in potential) per unit length of wire is called potential gradient i.e.
K = V/L
Where
V = Potential difference
L= length of the wire
K = 2.38/35 = 0.068 V/cm
19. How many turns of wire are needed to provide a potentiometer with a resolution of 0.05%?
500
5000
200
2000
Answer.4. 2000
Explanation:
Percent resolution (% R) of the potentiometer is given as:
% R = 100/Number of turns
Given: %R = 0.05%
0.05 = 100/Number of turns
N = 100/0.05
N = 2000 turns
20. DC potentiometer is an instrument to measure
Unknown emf
Large power
Unknown velocity
Low torque
Answer.1. Unknown emf
Explanation:
A DC potentiometer is an instrument designed to measure an unknown voltage by comparing it with the unknown voltage.
The known voltage may be supplied by a standard cell or any other known voltage reference source.
It makes use of a balance or null condition, no current flows, and hence no power loss is consumed in the circuit.
