Basic Electrical MCQ set 1

Transformers

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Objective Questions on Basic Electronics- Semiconductor, Integrated Circuits, Logic Gates

Objective Questions ELECTRONICS

The study of nature, control, and application of electrons

SEMI CONDUCTORS

Materials whose conductivity lies between conductors and insulators

SEMI CONDUCTORS ARE USED MAINLY IN

Solar cells (silicon)    transistors

DIODE

The electronic device which has semiconducting property that allows current to flow in one direction 

TRANSISTOR

A semiconductor device used to amplify or switch electronic signals and electrical power

INTEGRATED CIRCUITS (IC)

The circuits that act as transistors, diodes, resistors etc is called

GATES

The electronic circuit which works only on two voltage levels (0 and 1) is called 

LOGIC GATES ARE

1. AND Gate 

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 Basic Civil Engineering MCQ-set 3

1.Stones are obtained from rocks that are made up of:

a) Ores
b) Minerals
c) Chemical compounds
d) Crystals

Answer: b
Explanation: Rocks are made up of minerals. They can be monomineralic(single mineral) or polymineralic(more than one mineral).


2
The hot molten material occurring naturally below the surface of the Earth is called:

a) Lava
b) Slag
c) Magma
d) Tuff


Answer: c
Explanation: Hot molten material is called Lava when it erupts from a volcano and reaches the surface. Slag is waste material from smelting of ore. Tuff is a porous rock formed by consolidation of volcanic ash.


3
Which of the following is not a metamorphic change?

a) Calcite to schist
b) Limestone to marble
c) Shale to slate
d) Granite to gneisses

Answer: a

Explanation: Calcite is a carbonate mineral whereas schist is a metamorphic rock formed by metamorphosis of mudstone/shale to higher degree than slate.


4
Why is natural cement used very limitedly?
a) Brown in Colour
b) Standard consistency is not met with
c) Sets too quickly
d) Particle size is too fine

Answer: c
Explanation: Natural cement sets very quickly after addition of water and hence it is not quite workable. Artificial cement is preferred over this.

5
Who invented Portland cement and in which year?
a) William Aspdin, 1824
b) William Aspdin, 1840s
c) Joseph Aspdin, 1840s
d) Joseph Aspdin, 1824

Answer: b
Explanation: Joseph Aspdinpatented Portland cement in 1824. William Aspdin, his son is regarded as inventor of modern Portland cement due to his developments in 1840s.

6
What is the average particle size of cement?
a) 15 microns
b) 45 microns
c) 75 microns
d) 100 microns

Answer: a
Explanation: Approximately 95% of cement particles are smaller than 45 microns and the average particle size is 15 microns.

7
What is the meaning of soundness of cement?
a) Ability to flow when mixed
b) Ability to make ringing noise when struck
c) Ability to form strong and sound structure
d) Ability to retain volume after setting.

Answer: d
Explanation: When cement paste hardens and sets, it should not undergo any volume change. Soundness ensures this and is tested using Autoclave expansion test.

8
Time elapsed from the instance of adding water until paste ceases to behave as fluid is called:
a) Initial setting time
b) Final setting time
c) Intermediate setting time
d) Absolute setting time

Answer: a
Explanation: Final setting time is the time required for cement paste to reach certain state of hardness. Option c and d does not exist.

9
Which of the below mentioned is not a result of field test performed on cement?
a) There should not be any lumps
b) It should feel cold when you put your hand in bag of cement
c) The colourshould be blackish grey
d) It should not be gritty when rubbed with finger

Answer: c
Explanation: The colourof cement is normally grey with a greenish tint. There are different shades –lighter and darker, but it does not go as dark as blackish grey.

10
Which equipment is used to test setting time of cement?
a) Core cutter
b) Vibrator
c) Universal testing machine (UTM)
d) Vicatapparatus

Answer: d
Explanation: Core cutter is used to determine dry density of soil. Vibrator is used in sieve analysis. UTM can be used to test various parameters –tension, bending, shear of various materials. Vicatapparatus consists of a needle, used to penetrate the cement paste sample.

11
What is the initial setting time of cement?
a) 1 hour
b) 30 minutes
c) 15 minutes
d) 30 hours

Answer: b
Explanation: As per IS code 4031-part 5, the initial setting time of cement is minimum of 30 minutes. After this cement will start losing its plasticity and will not be workable.

12
Use of coarser cement particles leads to:
a) Low durability
b) Higher strength
c) Low consistency
d) Higher soundness

Answer: a
Explanation: For coarser particles, hydration starts on surface of particles, hence, it might not be completely hydrated. This causes low strength and low durability.

13
Wet cement can cause severe skin burns if not washed off with water immediately.
a) True
b) False

Answer: a
Explanation: Cement is highly alkaline and setting process is exothermic. Wet cement is strongly caustic and causes skin burns. Similarly, dry cement causes eye or respiratory irritation, when it comes in contact with mucous membranes.

14
What is the most dominant constituent of cement?
a) Silica
b) Lime
c) Magnesia
d) Alumina

Answer: b
Explanation: Cement contains about 60-65% of lime. Silica constitutes 17-25%, alumina 3-8% and magnesia 1-3%.

15
Deficiency of lime in cement leads to:
a) Unsound cement
b) Disintegration of cement
c) Quick setting of cement
d) Expansion of cement

Answer: c
Explanation: Presence of lime in sufficient quantity is necessary to form silicates and aluminates of calcium. Excess lime leads to expansion, disintegration and unsoundness of cement.

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