11.11.1999

**Electronic Inst.
And Meas.**

** **

**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.

- Express the factors in making measurements and
measurement errors.

- Express the operational principles of basic
analog dc ammeters.

- 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.

- 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 D
_{1}and D_{2}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 D_{2}.

**c-
****) **Calculate the values of series resistor R_{1},
R_{2}, and R_{3} 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.

Dr.A.N.Yazıcı

16.12.1999

- a-) For the given Hay Bridge Circuit, obtain the
expressions for unknown inductance L
_{x}and resistance R_{x}.

b-) The
quality factor Q of this circuit is determined as Q=_{}³10. Reduce the
expression of R_{x} and L_{x} 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.

- a-) The form factor (k) is known as the ratio of
the rms (E
_{rms}) to the average value (E_{av}) 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 = _{} %)

Dr.A.N.Yazıcı

19.01.2000

**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
(R_{X} and L_{X}) 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 R_{S}, L_{S}, C_{S}
and Q_{S} 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