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Multiple Choice Questions on Measurement and Instrumentation and Practice Test 4

By Global Rail Network on November 9, 2014

There are 9 questions to be attended in 20 minutes. The questions are on Measurement and Instrumentation. The study material is provided along with the remarks for each answer after you complete the examination to help building knowledge on the subject. It may be better to study before attempting the mock drill so that by the time you reach 9th of the test, you score is around 80-90%. There are 9 question banks of 9 question each and you should attempt each of these question bank to test your preparedness for the final day of the RRB examination for SSE and JE to be held in Dec.

There are 9 questions to be attended in 20 minutes. The questions are on Measurement and Instrumentation. Read the study material before making an attempt so that you build your confidence in the subject. This is the fourth of the series of 9 questions paper that will appear before the RRB examination for SSE and JE to be held in Dec.

Sl No.	Question	Answer	Remark
1	What value of shunt will be required to convert 50mA ammeter to 5 A ammeter when its internal resistance is 99 ohms?	1 Ω	Shunt resistance is given by the formula and equal to Ammeter Resistance divided by multiplying factor minus 1. The multiplying factor is 100, therefore shunt should be 99th part of the ammeter resistance.
2	Precision of a measuring device tells about	the degree of freedom from random error	“There are four characteristics of errors in measurement termed as Precision, Accuracy, Repeatability and Reproducibility having different application. Accuracy: The accuracy of an instrument is a measure of how close the output reading of the instrument is to the correct value. In practice it is quoted in terms of inaccuracy percentage on the measured value. Precision: It is a term that describes an instrument’s degree of freedom from random errors. If a large number of readings are taken of the same quantity by a high precision instrument, then the spread of readings will be very small.Repeatability: It describes the closeness of output readings when the same input is applied repetitively over a short period of time keeping all measurement conditions, instrument, observer, location and use similar.Reproducibility: It describes the closeness of output readings for the same input when there are changes in the method of measurement, observer, measuring instrument, location, conditions of use and time of measurement.”
3	Trilateration technique is widely used for the measurement of	Absolute or relative locations of points by measurement of distances	Trilateration is the process of determining absolute or relative locations of points by measurement of distances, using the geometry of circles, spheres or triangle
4	Principle of measurement of barometric pressure is also used for the measurement of	Altitude	Barometric pressure reduces with increase in altitude due to reduction in the weight of air column above it. Altitude is calibrated with pressure as z= c*log(P₀/P), where P is the pressure at altitude z.
5	A moving iron ammeter can be converted into a Voltmeter by	connecting a very high series resistance	By connecting a series resistance, the current the meter is restricted to its operative range. In all other three cases the current flowing through the meter coil is high and it will burn.
6	Capacitive displacement sensors are used for the measurement	all	Capacitive displacement sensors are non-contact devices capable of high-resolution measurement of the position and change of position of any conductive target. They are also able to measure the thickness or density of non-conductive materials. Capacitive displacement sensors are used in a wide variety of applications including semiconductor processing, assembly of precision equipment such as disk drives, precision thickness measurements, machine tool metrology and assembly line testing. It is used for the measurement of humidity as the permittivity of dielectric changes with humidity.
7	Hall effect states that	when a current carrying conductor is placed in a magnetic field at right angle, the electron deflects towards right angle to each	Hall effect: When a current carrying conductor is placed in a magnetic field such that the current flowing is perpendicular to the magnetic field. The electrons are defelected at perpendicular to both the current and magnetic field thus producing a potential at the opposite end. This tranverse voltage measured is called Hall voltage and made use in Hall effect sensor to be used as proximity switch, time and speed of the wheels and shaft, anti-locking braking system, brushless DC motor to detect the position of permanent magnet etc.
8	In air friction damping, the action of damping is observed	only when the piston moves in inward as well as outward direction
9	Hygrometer is a device used to measure the	humidity in air	Hygrometers are used measurement of air humidity. For specific gravity, hydrometers are used and measurement of depth is by barometric pressure

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Multiple Choice Questions on Measurement and Instrumentation and Practice Test 4

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