EP 485

Electronic Inst. And Meas.


  1. a- ) State the number of significant figures used in each of the following

i-) 22                ii-) 245.           iii-) 4.32           iv-) 256.322

            b- ) Find the arithmetic mean of the following data:

                                    12.2,  5,  8.5,  14.32,  7.5,  6.5,  6.5,  5.5

            c- ) Find the median of the following data

                                                5,  6,  4,  3,  2,  9,  7

            d- ) Find the mode of the following data

                                    5,  6,  4,  3,  4,  2,  4,  7,  2,  9,  4

e- ) An amplifier has an output signal of 3.6 Vrms when a sine wave input signal of 0.1 Vrms is present. State its gain in decibels.


  1. Express the factors in making measurements and measurement errors.


  1. Express the operational principles of basic analog dc ammeters.


  1. Design a multirange dc voltmeter with voltage ranges of 0-10 V, 0-50 V, 0-250 V, and 0-500 V using a basic d’Arsonval movement with internal resistance Rm=100 W and full-scale current Im=1 mA.


  1. The commercial voltmeter of below figure uses a 1 mA meter movement with an internal resistance of 100 W. The shunting resistance across the movement is 200 W. Diodes D1 and D2 each have a forward resistance of 200 W and infinite reverse resistance.

a-   ) Explain the function of the shunting resistor across the meter movement.

b-   ) Explain the function of the diode D2.

c-    ) Calculate the values of series resistor R1, R2, and R3 if the required meter ranges are 10

        V. 50 V, and 100 V, respectively.

d-   ) Determine the ohm-per-volt rating of this ac voltmeter.











                                                                                                                        Good Luck







EP 485
Electronic Inst. And Meas.



  1. a-) For the given Hay Bridge Circuit, obtain the expressions for unknown inductance Lx and resistance Rx.

b-) The quality factor Q of this circuit is determined as Q=³10. Reduce the expression of Rx and Lx to the their simplest form using the expression of Q.

c-) Discuss how can you measure the unknown value of applied frequency (w or f) using this circuit.














2.      Firstly draw the simple circuit diagram of a laboratory-type Cathode Ray Oscilloscope (CRO) and then explain its function and describe its operational principle.


  1. a-) The form factor (k) is known as the ratio of the rms (Erms) to the average value (Eav) of a waveform which can be sinusoidal or nonsinusoidal. Calculate the numerical value of form factor (k) for a sinusoidal waveform.

b-) An average responding electronic ac voltmeter with an rms-calibrated scale is used to measure the following nonsinusoidal voltage waveforms. The symmetrical square and triangular wave voltages with an amplitude of 10 Volt. Calculate the form factors (k) of both waveforms.

c-) Calculate the percentage error indicated by the ac voltmeter for each of the voltages cited.

            (Hint : Percentage Error =  %)


Good Luck






EP 485 Elec.Inst.and Meas.

Final Exam (Time Duration : 100 Mins.)


1.      a-) The following prices are found for a certain brand of canned peas over a period of six weeks : $1.96, $2.05, $1.75, $1.94, $2.25, $2.10. Calculate both the arithmetic mean and the harmonic mean.

b-) Find the mean and standard deviation of the following set of weight measurements :

      1.6       1.45    1.4       1.5       1.6

      1.4       1.5       1.6       1.55    1.4

c-) Calculate the standard error of the mean for the sample in 1.b, and report it in the standard manner.



2.      a-) Design an electrical circuit and then

 obtain necessary equation to measure

 the unknown impedance values.

b-)  Determine the unknown component

 values  (RX and LX) in the given

 circuit in Fig.1.



3.      a-) A coil with a resistance of 10 W is

connected in the “direct – measurement”

mode in Q-meter. Resonance occurs when

the oscillator frequency is 1.0 MHz and

the resonating capacitor is set at 65 pF.

Calculate the percentage error introduced

in the calculated value of Q by the 0.02 W insertion resistance. 

b-) Obtain the equation of RS, LS, CS and QS for series connection in Q-meter.


4.      a-) Explain the operational principle of a cathode ray oscilloscope (CRO).

b-) In Fig.2.a., find the frequency of the waveform if the time base is set to 0.5 ms/div.

c-) In Fig.2.a., find the rms amplitude of the waveform if the vertical attenuator is set to 2 V/div.

d-) In Fig.2.b., find the period of the waveform if the time base is 10 ms/div.

e-) In Fig.2.b., find the amplitude if the vertical attenuator is set to 1 V/div.

f-) In Fig.2.b., find the slope of the leading edge of the waveform.






Figure 2