Practice Pakistan's most useful MCQs for competitive exams

Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a __________________?

• (A)  Thermocouple
• (B)  Resistance thermometer
• (C)  Mercury in glass thermometer
• (D)  Vapor pressure thermometer

Answer

Submitted By :Ali Uppal

Time constant is the __________________?

• (A)  Time taken by the controlled variable to reach 63.2% of its full change
• (B)  Same as transportation lag
• (C)  Same as dead time
• (D)  Time required by the measured variable to reach 63.2% of its ultimate change

Answer

Submitted By :Ali Uppal

What is the dynamic error in a critically damped second order instrument for a ramp input (At) ?

• (A)  0.5 AT
• (B)  2 AT
• (C)  √(AT)
• (D)  1.5 AT

Answer

Submitted By :Ali Uppal

Emf developed by a thermocouple while measuring a temperature of 400°C is 22 mV. The type of thermocouple used is ___________________?

• (A)  Chromel-alumel
• (B)  Iron-constantan
• (C)  Platinum-rhodium
• (D)  Platinum-platinum + rhodium

Answer

Submitted By :Ali Uppal

An amplitude ratio of 0.1 corresponds to _____________ decibels?

• (A)  20
• (B)  -20
• (C)  10
• (D)  -10

Answer

Submitted By :Ali Uppal

Transfer function of transportation lag is___________________?

• (A)  eTS
• (B)  e-TS
• (C)  1/(Ts + 1)
• (D)  None of these

Answer

Submitted By :Ali Uppal

Suppose that the gain, time constant and dead time of a process with the following transfer function: Gc(s) = 10 exp( – 0.1s)/(0.5s + 1) are known with a possible error of ± 20% of their values. The largest permissible gain Kc of a proportional controller needs to be calculated below taking the values of process gain, time constant and dead time as________________?

• (A)  8, 0.6, 0.08
• (B)  12, 0.6, 0.12
• (C)  8, 0.6, 0.12
• (D)  12, 0.4, 0.08

Answer

Submitted By :Ali Uppal

Paramagnetism method is not used for the composition determination of ______________ in gases?

• (A)  Oxygen
• (B)  Oxides of nitrogen
• (C)  Carbon dioxide
• (D)  Any of these

Answer

Submitted By :Ali Uppal

The frequency response of a dynamic element shows a constant magnitude ratio at all frequencies. The element exhibits a negative phase shift at all frequencies. The absolute value of the phase shift increases linearly with frequency. The element has the transfer function ?

• (A)  e-ηS
• (B)  (T1S + 1)/(T2S + 1)
• (C)  (T1S/(T2S + 1)
• (D)  (T1S + 1)/(T2S

Answer

Submitted By :Ali Uppal

E.m.f. generated by thermocouples is of the order of ________________?

• (A)  Milli volts
• (B)  Micro volts
• (C)  Volts
• (D)  Kilo volts

Answer

Submitted By :Ali Uppal