Engineering Questions with Answers - Multiple Choice Questions
MCQs on Interfacing to the Analog World
1 - Question
MCQs on Codecs
From which of the following words does codecs is derived?
a) coder
b) decoder
c) coder-decoder
d) coder-encoder
View Answer
Explanation: The codec is derived coder-decoder and is coupled to perform the coding. It can support both analogue to digital conversion and digital to analogue conversion.
2 - Question
Which codec is used in digital audio?
a) A-law
b) µ-law
c) linear
d) PCM
View Answer
Explanation: In the linear codec, the relationship between the analogue and digital values are linear. This method is commonly used in digital audio communication.
3 - Question
Which of the following have the same quantisation step throughout the range?
a) linear
b) PCM
c) DPCM
d) ADPCM
View Answer
Explanation: The quantisation step is same throughout the dynamic range in the linear codec and thus any increase in the analogue value increases the digital value, that is, the overall performance is linear. advertisement
4 - Question
Which is used in the telecommunication applications which has a limited bandwidth of 300 to 3100 HZ?
a) linear codec
b) logarithmic codec
c) PCM
d) DPCM
View Answer
Explanation: The logarithmic codec is frequently used in the telecommunication system which have a limited bandwidth of 300 to 3100 Hz. this can provide an 8-bit sample at 8 KHz, which are used in the telephones. The commonly used are A-law and µ-law.
5 - Question
Which codec is used in the UK?
a) a-law
b) µ-law
c) linear codec
d) PCM
View Answer
Explanation: The a-law is a logarithmic codec which is commonly used in the UK whereas µ-law is used in the US.
6 - Question
What does PCM stand for?
a) pulse codec machine
b) pulse code modulation
c) peripheral code machine
d) peculiar code modulation
View Answer
Explanation: The linear codec is also known as pulse code modulation which is commonly used in the telecommunications industry.
7 - Question
Which of the following conversion is performed by using a lookup table?
a) DPCM
b) ADPCM
c) Between DPCM and ADPCM
d) Linear cdec and a-law
View Answer
Explanation: The conversion between a-law/µ-law and a linear digital signal or between µ-law and a-law is performed by a lookup table.
8 - Question
What does DPCM stand for?
a) differential pulse code modulation
b) data pulse code modulation
c) dynamic pulse code machine
d) dynamic pulse code modulation
View Answer
Explanation: The differential pulse code modulation is similar to pulse code modulation, but DPCM uses an encoded value which is the difference between the current and the previous sample.
9 - Question
Which of the following have a 16-bit digital dynamic range?
a) PCM
b) DPCM
c) linear codec
d) logarithmic codec
View Answer
Explanation: The differential pulse code modulation can improve the accuracy and resolution by having a 16-bit dynamic range. It works by the increasing dynamic range.
10 - Question
How many types of logarithmic codecs are used commonly?
a) 2
b) 3
c) 4
d) 5
View Answer
Explanation: There are two types of logarithmic codec which are commonly used. They are a-law which is used in UK and µ-law codec which is used in the US.
11 - Question
What does ADPCM stand for?
a) address differential pulse code modulation
b) adaptive differential pulse code modulation
c) address dynamic pulse code machine
d) adaptive dynamic pulse code modulation
View Answer
Explanation: The adaptive differential pulse code modulation is used in telecommunications and is based on non-linear quantisation values.
12 - Question
Which of the following uses a non-linear quantisation value?
a) PCM
b) DPCM
c) ADPCM
d) linear codec
View Answer
Explanation: The adaptive differential pulse code modulation is based on non-linear quantisation values. In the ADPCM, instead of using all bit for encoding, only a few bits are used for encoding which makes it non linear.
13 - Question
Which of the following works by increasing the dynamic range?
a) logarithmic codec
b) linear codec
c) DPCM
d) PCM
View Answer
Explanation: The differential pulse code modulation can improve the accuracy and resolution by having a 16-bit dynamic range. It works by the increasing dynamic range.
14 - Question
Which device can make the PWM operation easier?
a) timer
b) software
c) hardware
d) transistor
View Answer
Explanation: The timer can be used for making up the PWM waveform far more easier and faster and it will free the processor to do other things without affecting the timing.
15 - Question
MCQs on Power Controls
Which of the following can be used for providing high gain?
a) transistor
b) darlington transistor pair
c) resistor
d) capacitor
View Answer
Explanation: The darlington pair of transistors can provide high gain than a single transistor. This is one of the method used to avoid voltage mismatches that the system produces. By using high gain transistors the voltage mismatches can be reduced upto a limit.
16 - Question
Which devices have high drive capability?
a) transistor
b) fet
c) buffer pack
d) darlington amplifier
View Answer
Explanation: The buffer pack is used to avoid the voltage mismatches which possesses a high drive capacity and it can also provide high drive currents than the normal logic outputs.
17 - Question
Which of the following is used to switch heavy loads?
a) fet
b) transistor
c) buffer pack
d) darlington pair
View Answer
Explanation: The field effect transistor can be used to provide a very high effective gain and hence they can be used to switch heavy loads easily from a logic device. These are also voltage controlled transistors.
18 - Question
Which allows the switching of DC motor by using two outputs and four FETs?
a) transistor
b) H bridge
c) darlington pair
d) buffer pack
View Answer
Explanation: The H bridge can be created by using several switches which allows a DC motor to be switched on and reversed in the direction. The switching can be done by using two outputs and four FETs. advertisement
19 - Question
Which of the following is used to create H bridge?
a) switches
b) led
c) capacitor
d) inductor
View Answer
Explanation: The H bridge can be created by using several switches. This allows a DC motor to be switched on and reversed in the direction and the switching of DC motor can be done by using two outputs and four FETs.
20 - Question
Which of the following allows voltage reversing?
a) H bridge
b) Relays
c) LEDs
d) LCDs
View Answer
Explanation: The H bridge is used in controlling DC motors or any other loads which need voltage reversing.
21 - Question
Which devices are used as indicators in a digital system?
a) LCD
b) LED
c) Varactor diode
d) Gunn diode
View Answer
Explanation: The light emitting diodes are used as indicators in the digital system and can be directly driven from a logic output.
22 - Question
How is the biasing done in LEDs?
a) forward bias
b) no bias
c) supply voltage
d) reverse bias
View Answer
Explanation: The LEDs will light up only when the diode reverse breakdown is achieved. It is usually about 2 to 2.2V.
23 - Question
Which of the following determines the brightness of LEDs?
a) current
b) voltage
c) resistance
d) conductance
View Answer
Explanation: The current drive determines the brightness of the LEDs and it is usually associated with a current limiting resistor in series with the LED to prevent the overheating.
24 - Question
Which of the following is a current limiting device?
a) voltage
b) current
c) buffer
d) inductor
View Answer
Explanation: A buffer can be used as a current limiting device. Similarly, a transistor can also be used as a current limiting device.
25 - Question
Which of the following can switch the current by a make or break contact?
a) transistor
b) relay
c) buffer
d) fet
View Answer
Explanation: The relays are a kind of switching power in which the logic signal is used to energise the relay. The relay contacts are break or make accordingly and helps in switching the current.
26 - Question
Which of the following generates a back EMF?
a) relay
b) buffer
c) transistor
d) FET
View Answer
Explanation: The relay generates a back voltage across its terminals when the logic output switches from a high to low state.
27 - Question
Which of the following is used to avoid the back EMF in the relay?
a) resistor
b) capacitor
c) inductor
d) diode
View Answer
Explanation: In order to get rid of the back EMF which is generated by the relay a diode is connected across the terminals which operate in the reverse bias so that nothing can harm the relay.
28 - Question
Which of the following can provide a speed control technique in the DC motor interfacing?
a) PCM
b) DPCM
c) ADPCM
d) PWM
View Answer
Explanation: The pulse width modulation can provide a speed control technique in the DC motor interfacing by changing its mark/space ratio.
29 - Question
Which of the following possesses some loops for providing timing functions?
a) hardware
b) software
c) timer
d) counter
View Answer
Explanation: In the software system, certain loops perform the timing functions. A program is created to switch the motor on and it will start counting through a delay loop. When the count is finished, the motor is switched off. In the second delay loop, it can determine the motor-off period.