Multiple choice question for engineering
1. How many, time base generators are provided to a CRO?
Answer: a [Reason:] A Cathode Ray Oscilloscope has two time base generators. A time base generator has various sweep modes based on the complexity of the second time base generator.
2. TTL trigger mode is not used for any purpose.
Answer: b [Reason:] The TTL trigger mode in a Cathode Ray Oscilloscope is useful in the case of ringing effects. Ringing effects lead to the formation of unwanted oscillations due to switching transients.
3. CRO waveform is disturbed due to
a) Capacitor banks
b) RTL triggering
c) TTL triggering
d) Voltage sources
Answer: c [Reason:] In a Cathode Ray Oscilloscope, the waveform is affected as a result of TTL trigger mode. The lead inductance of the ground along with probe capacitance results in a resonance circuit.
4. Ringing effects can cause false triggering.
Answer: a [Reason:] The TTL trigger mode in a Cathode Ray Oscilloscope is useful in the case of ringing effects. Ringing effects produce false triggering even though the trigger points may not be set.
5. How can false triggering be prevented?
a) using RTL logic
b) using TTL logic
c) using DTL logic
d) using flip flops
Answer: b [Reason:] In a Cathode Ray Oscilloscope, TTL trigger circuit is used for setting the correct trigger points. The trigger circuit acts in the same way as the input of a TTL circuit.
6. What is the significance of the TTL trigger mode?
a) initiates interference
b) attenuates the signal
c) prevents interference
d) boosts the signal
Answer: c [Reason:] In a Cathode Ray Oscilloscope, TTL trigger circuit prevents sweep signals that are below the trigger gap from getting triggered falsely.
7. TTL triggering gives a
a) attenuated output
b) magnified output
c) unstable output
d) stable output
Answer: d [Reason:] TTL triggering circuit in a Cathode Ray Oscilloscope gives rise to a stable display. There is no necessity to check the TTL levels on the screen. The logic levels are also checked to be correct.
8. Switched sweep mode is also known as
a) dual sweep mode
b) single sweep mode
c) quadruple sweep mode
d) triple sweep mode
Answer: a [Reason:] A switches sweep mode is used for displaying two independent variable sweep modes in an alternative fashion. Initially a waveform is displayed with a slow sweep rate and then with a fast sweep rate.
1. Strain gauges are classified into ________
a) 3 types
b) 5 types
c) 7 types
d) 9 types
Answer: a [Reason:] Strain gauges can be classified into three broad categories based on the principle of operation and construction. They are mechanical, optical and electrical.
2. Resistance wire gauges come in _______
a) 4 forms
b) 2 forms
c) 6 forms
d) 8 forms
Answer: b [Reason:] Strain gauges made out of electrical wires come in two broad forms. They are as follows:
3. Bonded resistance wire strain gauge is of _______
a) 7 types
b) 5 types
c) 3 types
d) 9 types
Answer: c [Reason:] The bonded electrical wire resistance strain gauge is broadly classified into three main types. They are as follows:
• Flat grid
• Helical grid
• Thin foil.
4. Commonly used electrical strain gauge is _______
a) open type
b) closed type
c) unbounded type
d) bonded type
Answer: d [Reason:] Electrical strain gauges are a type of strain gauge. The commonly used electrical strain gauge is the bonded resistance type. Capacitance and inductance types are used in special types of applications.
5. Electrical strain gauges measure changes in _______
a) resistance, capacitance and inductance
b) resistance only
c) capacitance only
d) inductance only
Answer: a [Reason:] Strain is transferred between the specimen and the gauge element in a strain gauge. Electrical strain gauges measure the changes occurring in resistance, capacitance and inductance.
6. Mechanical gauges measure the _______
a) change in resistance
b) change in length
c) change in area
d) change in inductance
Answer: b [Reason:] A mechanical gauge is used to measure the change in length. They make use of gears. Mechanical gauges are used for static strain measurements only.
7. Optical gauges make use of _______
d) rack and pinion
Answer: c [Reason:] Optical gauges are similar to mechanical gauges. They make use of prisms and mirrors for obtaining magnification. A plain mirror is fixed onto a movable knife edge.
8. Tensile stress decreases the length.
Answer: b [Reason:] Tensile stress tends to elongate a wire. As a result its length increases and its area of cross-section decreases.
9. In a foil strain gauge, strain is detected through _______
a) a capacitance element
b) a resistance wire
c) a gold foil
d) a metal foil
Answer: d [Reason:] Strain is detected in a foil strain gauge by making use of a metal foil. The foil makes use of nickel, nichrome, constantan, isoelastic and platinum.
10. Etched foil strain gauges are flexible.
Answer: a [Reason:] Etched foil strain gauges are a type of foil strain gauge. Compared to resistance wire gauges, they can be made thinner. They are also flexible. Etched foil strain gauges are made use o curved surfaces.
1. Input impedance of a voltmeter is ___________
Answer: a [Reason:] In order to prevent the loading effect in a voltmeter, the input impedance is maintained as high as possible. It must be maintained higher than the impedance of the circuit being used.
2. Input impedance depends on _________
Answer: b [Reason:] Shunt capacitance appearing across the input terminals affects the input impedance. Capacitive reactance of the capacitance is inversely proportional to the frequency.
Xc ∝ 1⁄f where, Xc is the capacitive reactance
f is the frequency.
3. At high frequencies the capacitive reactance.
a) is constant
d) becomes zero
Answer: c [Reason:] We know that the capacitive reactance is inversely proportional to the frequency.
Xc ∝ 1⁄f At high frequencies, the capacitive reactance becomes very small.
4. Voltage ranges in a meter are _________
Answer: d [Reason:] Meter scale will have a calibration of 1-3-10 for the voltage range with a separation of 10 dB. It can also be in the sequence of 1.5-5-15. We can also make use of a single scale.
5. Linear meter with 1% accuracy must have _________
a) 100 divisions
b) 50 divisions
c) 200 divisions
d) 500 divisions
Answer: a [Reason:] In order to recognise a reading with 1% accuracy it must have 100 divisions on the 1 V range.
6. Decibel covers a small range of values.
Answer: b [Reason:] As the unit decibel makes of the logarithmic scale, it covers a wide range of values of any given quantity.
7. Noise is a function of _________
Answer: c [Reason:] Noise in general depends on the value of the bandwidth. Voltmeter having a large bandwidth takes up more noise. Usually the sensitivity of a voltmeter is 1mV for a bandwidth of 10Hz – 10MHz.
8. Current can be measured effectively by making use of _________
a) d.c. voltmeter
b) a.c. ammeter
c) d.c. ammeter
d) a.c. voltmeter
Answer: d [Reason:] By making us e of a a.c. voltmeter in series with a resistance we can obtain the current value. We can also make use of the current probe method to obtain the value of the current without effectively disturbing the circuit.
9. Average responding voltmeter is cheap and accurate.
Answer: a [Reason:] Average responding voltmeter is used for a.c. measurements for sine wave with 10% distortion or less. Hence the average responding voltmeter is cheap and accurate.
1. What is the chemical composition of Quartz?
Answer: c [Reason:] The chemical composition of the quartz minerals is SiO2. In other words, silicon dioxide is the basic chemical composition of the quartz minerals.
2. Which quartz mineral shows blue colour?
a) Rose quartz
b) Blue quartz
c) Smoky quartz
d) Rock crystal
Answer: b [Reason:] The blue quartz shows a distinct blue colour compared to the other quartz minerals.
3. Rock crystal belongs to which mineral group?
a) Quartz group
b) Feldspar group
c) Carbonate group
d) Ferro-magnesium group
Answer: a [Reason:] The basic chemical composition of the rock crystal is almost the same as other quartz minerals and also rock crystal is an important mineral of the quartz group.
4. Pick the quartz mineral which is translucent among the following.
a) Rose quartz
c) Amethyst quartz
d) Milky quartz
Answer: c [Reason:] Amethyst quartz is usually translucent, i.e., it allows light partially to pass through it. Rest of the minerals are opaque.
5. The streak given by the quartz group is
d) Pale yellow
Answer: b [Reason:] One of the main trait of the quartz group is that the minerals do not give any streak though are present in many colours in appearance.
6. Pick the quartz which is colourless among the following.
a) Rose quartz
b) Smoky quartz
c) Milky quartz
d) Rock crystal
Answer: d [Reason:] Among the minerals given above only rock crystal is colourless. The rest are coloured or either white in colour.
7. What is the hardness of the quartz minerals?
Answer: a [Reason:] The hardness is almost the same for all the quartz minerals and is about 7. This is one of the advantages of the quartz as they have high hardness.
8. What is the colour of rose quartz attributed to?
Answer: b [Reason:] Rose quartz is a special type of quartz and is known for its distinct rose red colour. The colour is attributed to presence of titanium.
9. The mineral not belonging to the quartz group is
Answer: d [Reason:] Amethyst quartz, agate and jasper belong to the quartz group, whereas, calcite belongs to the carbonate group whose chemical composition is completely different compared to the quartz group.
10. Agate is not found banded. State true or false.
Answer: b [Reason:] Agate is also found in banded form and is known as banded agate. Agate is known to have massive structure which is also the same for banded agate.
11. What is the cleavage shown by quartz minerals?
d) No cleavage
Answer: d [Reason:] The cleavage is generally absent in the quartz minerals which is one of the defining characteristic of the quartz group.
12. Quartz is found in which type of rock?
a) Igneous rock
b) Sedimentary rock
c) Metamorphic rock
d) Igneous, sedimentary and metamorphic rocks
Answer: d [Reason:] Quartz minerals are found in wide range of rocks. They are not restricted to any one kind of rock. They may be found in igneous or sedimentary or metamorphic rocks.
1. Slate is originated from which rock?
Answer: c [Reason:] Slate is a product of low-grade regional metamorphism of argillaceous rocks like clays and shales.
2. Low grade schist is formed under what conditions
a) Low temperature and local metamorphism
b) High temperature and local metamorphism
c) Low temperature and regional metamorphism
d) Low temperature and regional metamorphism
Answer: c [Reason:] Low grade schists are formed under conditions of regional metamorphism at low temperature. These are rich in minerals like albite, muscovite and chlorite that are unstable at high temperature.
3. What is the grain size of slate rock?
d) Very coarse
Answer: a [Reason:] Slate is an extremely fine-grained metamorphic rock characterized by a slaty cleavage by virtue of which it can be readily split into thin sheets having parallel smooth surfaces.
4. High grade schist is formed under what conditions?
a) Local metamorphism
b) Regional metamorphism
c) Displacement metamorphism
d) Chain metamorphism
Answer: b [Reason:] High grade schists are formed under conditions of regional metamorphism and atoms rich in minerals that are stable at high temperatures such as garnet.
5. Examples of high grade schist is
a) Talc- schist
Answer: b [Reason:] Garnet-schists, cordierite-schists and staurolite-schists are common examples of some high grade schists.
6. Special property of talc schist is
b) Its structure
c) Soapy feel
d) Good odour
Answer: c [Reason:] Talc schist is a low grade schist and its special property is that it gives a soapy feel when touched with bare hands.
7. Gneiss formed from sedimentary rock is called
c) Banded gneiss
d) Augen gneiss
Answer: b [Reason:] Paragneiss are formed from the metamorphism of sedimentary rocks like sandstone. Orthogneiss formed as a result of metamorphism of granites and other igneous rocks.
8. The similar type of rock to quartzite which is sedimentary is
a) Compound quartzite
Answer: b [Reason:] The name orthoquartzite is used for a sedimentary rock of similar composition but having different origin, in which quartz grains are cemented together by siliceous cement.