EC
Engineering Classroom
by Himalay Sen

Exams

Prepare for your next test with our collection of exam-based practice sets and question banks designed for effective assessment and revision.

Board Questions

Access past board exam questions organized by year and subject to help you understand patterns, improve preparation, and boost your exam performance.

MCQ
102. As compard to overhead system, the maintenance cost of underground system is--
very high
very low
same
none above
ব্যাখ্যা: ব্যাখ্যা: As compared to overhead system, the maintenance lost of underground system is very low. In underground system, there is less possibility to occur fault as compared to overhard system. If any fault is occured at a specific place the fault point should be maintained which is low cost.
103. ক্যাবল বা কোরের প্রতি একক দৈর্ঘ্যের রেজিস্ট্যান্স জানা থাকলে যে টেস্ট উপযোগী, তা-
সাবস্টিটিউট টেস্ট
র‍্যাভিয়ার টেস্ট
মারি লুপ টেস্ট
ভারলি লুপ টেস্ট
104. When a load of leading pf the full load secondary voltage of a transformer is-its no-
load voltage.
equal to
greater than
less than
ব্যাখ্যা: ব্যাখ্যা: ফুল-লোড ভোল্টেজ যখন নো-লোড ভোল্টেজ অপেক্ষা বেশি হবে তখন লোডের পাওয়ার ফ্যাক্টর হবে লিডিং এবং ভোল্টেজ রেগুলেশনের ঋণাত্মক মান পাওয়া যাবে।
105. Ferranti effect will not occur in which of the transmission lines?
long transmission line
short transmission line
medium transmission line
all of these
ব্যাখ্যা: ব্যাখ্যা: Ferranti effect occurs in case of no load or light load condition of medion and long transmission lines due to copacitance effect of the transmission lines. In case of short transmission lines, the cuparitance effect is negligible. Therefore, Jerranti effect will not occur in short transmission lines
107. Under the condition of maximum power transfer, the efficiency is --
100%
50%
75%
25%
ব্যাখ্যা: ব্যাখ্যা: The power efficiency is 50% at maximum power transfer (Other 50% is dissipated at source impedance
108. Advantages of higher transmission voltage is/are-
power transfer capability of the transmission line is increase
transmission line losses are reduced
area of cross section and volume of the conductor is reduced
all of those
109. লুপ টেস্টের একটি সুবিধা এই যে-
ফল্টের রেজিস্ট্যান্স প্রাপ্ত ফলের উপর প্রভাব বিস্তার করে
ফল্টের রেজিস্ট্যান্স প্রাপ্ত ফলের উপর প্রভাব বিস্তার করে না
ফল্টের রেজিস্ট্যান্স প্রাপ্ত ফলের উপর নির্ভর করে ফল্টের রেজিস্ট্যান্স প্রাপ্ত ফলের উপর নির্ভর করে না
ফল্টের রেজিস্ট্যান্স প্রাপ্ত ফলের উপর নির্ভর করে ফল্টের রেজিস্ট্যান্স প্রাপ্ত ফলের উপর নির্ভর করে না
110. How many electricity distribution utilities are there in Bangladesh?
4
6
5
none
ব্যাখ্যা: ব্যাখ্যা: বাংলাদেশে বিদ্যুৎ বিতরণকারী প্রতিষ্ঠান হলো ৬টি, যথা- BREB, BPDB, NESCO, WZPDCL, DESCO, DPDC
111. The transmission lines generally use-
copper
all aluminium conductor
ACSR conductor
none
ব্যাখ্যা: ব্যাখ্যা: These cables are formally known as All Aluminium Conductor (AAC). These overhead aluminium conductors are used as power transmission.
112. The effect of corona is-
increased energy loss
increased reactance
increased inductance
all of above
ব্যাখ্যা: ব্যাখ্যা: The phenomenon of ionisation of surrounding air around the conductor of transmission line due to which luminous glow with hissing noise is rise is known as the corona effect.
113. Corona occurs between when they-
two transmission lines are closely-spaced
are widely-spaced
high-potential difference
carry d.c power
ব্যাখ্যা: ব্যাখ্যা: The phenomenon of ionisation of surrounding air around the conductor due to which luminous glow with hissing noise is rise is known as the corona effect. Corona occurs between two transmission lines when they have high potential difference.
114. What is to be added in an electric line to increase voltage?
Capacitor
Resistor
Inductor
All
ব্যাখ্যা: ব্যাখ্যা: Increase the total working voltage of two capacitors by connecting them in series.
115. Which of the following statement is true?
at higher voltage cost of transmission is reduced
at higher voltage cost of transmission is increased
at higher voltage efficiency is increased
all of these
ব্যাখ্যা: ব্যাখ্যা: At higher voltage, volume of conductor is reduced. Area of conductor AI/V Where V. Supply voltage. So that material requirement is reduced and hence cost of the material and transmission reduced.
117. Objectives of power system is/are-
cost of electrical energy per kWh is to be minimum
rated voltage and frequency has to be supplied to the consumers
both a & b
neither a or b
ব্যাখ্যা: ব্যাখ্যা: (i) Cost of electrical energy per kWh is to be minimum (il) Rated voltage and frequency has to be supplied to the consumers. (iii) Reliable power has to be available. (iv) Effective protection system has to be used for isolating the faulty section and keeping other sections healthy. (v) More stable generators are to be used, so that it should not lose synchronism under faulty condition. (iv) Flexible power has to be available.
118. কমিউনিকেশন লাইনে ফল্ট নির্ণয়ের জন্য যে টেস্ট করা হয়, তা-
মারি লুপ টেস্ট
ভারলি লুপ টেস্ট
ব্ল‍্যাভিয়ার টেস্ট
সাবস্টিটিউট টেস্ট
119. Corona is observed on--
ac transmission lines only
dc transmission lines only
both a & b
none
ব্যাখ্যা: ব্যাখ্যা: Corona is observed on AC transmission line only Because in AC transmission line there is focx associated
120. The absolute zero temperature is taken as-.
-273°C
237°C
273°C
-237°C
ব্যাখ্যা: ব্যাখ্যা: Absolute zero is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as zero kelvins. The fundamental particles or nature have minimum vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion. The theoretical temperature is determined by extrapolating the ideal gas law; by international agreement, absolute zero is taken as-273.15° on the Celsius scale (International System of Units), which equals-459.67° on the Fahrenheit scale (United States customary units or Imperial units). The corresponding Kelvin and Rankine temperature scales set their zero points at absolute zero by definition.