Classes of amplifier operations: Class A B C

Q 1. Which class of amplifier has the lowest efficiency ?

   (a)Class A   (b)Class B   (c)Class C  (d)Class AB


Q2.A push pull amplifier is biased

(a) Class A    (b)Class C   (c) Class AB     (d)Class B


Q3 Maximum efficiency of a Class A amplifier is

 (a) 50%              (b)78.5 %       (c)80%   (d)100%


Q4 Which of the follwing typs of  amplifiers corresponds to a half wave rectifier ?

 (a)Class A   (b)Class B   (c)Class C    (d)class AB


Q5 Which type of power amplifier is biased for operation at less than 180º of the cycle?

(a)Class A   (b)Class B   (c)Class C    (d)class AB



_____________________________SOLUTIONS____________________________________
Q1.Ans: a

Q2. Ans: d,In Class B operatio, the linear operation of Class A can be obtained by using two matched transistors in push pull , each of them operating for half of the input signal period.
Q3. Ans b
Memorise the Hint:
ɳ CLASS Cab BA amplifier ==>i.e 100% ,50-78.5%,78.5%,50%  
Distortion proportional to Efficiency.
Conduction angle ===> Class C 90, class B 180,Class A 360

	class C	Class AB	Class B	Class A
Efficiency ɳ	100%	50% -78.5 %	78.5%	50%
Conduction angle	small (~90 Degree)	360 to 180 Degree	180 Degree	360 Degree
Bias	Revote	Forward	zero	Forward
Distortion	Extream	Moderate	High	Low

Q4. Ans b

Q5. Ans c

Basic Electrical/Network theorems/Set-1/Paper-02

1. Kirchoff's current law states that

(a)net current flow at the junction is positive
(b)Algebraic sum of the currents meeting a junction is zero
(c)no current can leave the junction without some current entering it.
(d)total sum of currents meeting at the junction  is zero

Ans:b

2. According to Kirchoff's voltage law , the algebraic sum of all IR drops and emfs in any closed loop of a network is always

(a)negative (b)positive (c) determined by battery emfs (d) zero

Ans: d

3.Kirchoff''s current law is applicable to only

(a)junction in a network (b)closed loops in a network (c)electrical circuits (d)electronic circuits

Ans:a

4. Which of  the following is no linear  circuit parameter ?

(a)Inductance (b)Condenser (c)wire wound resister (d)Transistor

Ans: a

5. A capacitor is generally a

(a)bilateral and active component
(b)active , passive linear and nonlinear component
(c)linear and bilateral component
(d)non-linear and active component

Ans: c

6. The circuit whose properties are same in either directions is known as

(a)unilateral circuit (b)bilateral circuit (c)irreversible circuit (d)reversible circuit

Ans:b


7. The circuit has resistor, capacitor and semiconductor diode the circuit will be

(a)non linear circuit (b)linear circuit (c)bilateral circuit (d)none of the above

Ans: a

8. A non-linear network does not satisfy

(a)superposition condition (b)homogeneity condition (c) both a and b (d)none of these

Ans:c

9. A network which contains one or more than one source of emf is known as

(a)linear network (b)non linear network (c)passive network (d)active network

Ans: d

10. Kirchoff''s voltage law is related to
(a) junction current   (b) battery emfs    (c) IR drops    (d) both b and c

Ans:d

IP address basic concept in networking

Internet Protocol (IP) address:

An identifier for a computer or device on a TCP/IP network. Networks using the TCP/IP protocol route messages based on the IP address of the destination. The format of an IP address is a 32-bit numeric address written as four numbers separated by periods(192.168.1.1). Each decimal number represents eight bits of binary data, and therefore can have a decimal value between 0 and 255.

Subnet Mask:

A subnet mask is used to divide an IP address  into two parts.One part is identifes the the host (computer) , the other part identifies the network which belongs.

The first part of an IP address is used as a network address, the last part as host address.

If you take an example 192.168.1.132 and divide it into these two parts you gets the following

192.168.1.0   Network Address

 0.0.0.132      Host Address

For this example  using 255.255.255.0 subnet mask

When a packet arrives on the 192.168.1.0 subnet and it has a designation address of 192.168.1.132 , computer will receive it from the network and process it.

This means that you can use the address 192.168.1.1 to 192.168.1.254 for your computers  to connect in the network.

The number after the slash represents the number of consecutive 1's in the subnet mask.

For example 192.168.1.0/24 is equal to the network   192.168.1.0 with  255.255.255.0   sub net mask.

Network address:  192.168.1.0/24      

First computer IP address: 192.168.1.3                                                           Second computer IP address: 192.168.1.4

Third computer IP address: 192.168.1.5                          

Subnet mask: 255.255.255.0

Gate way : 192.168.1.2 (Router IP address) 

If you convert 255.255.255.0 to binary , you end up with 24 consecutive 1 's

11111111.11111111.11111111.00000000

IP                                         subnet mask

192.168.1.0/24              255.255.255.0                  

   

192.168.1.0 to 192.168.1.255     Total - 256 host address  

Adress:	192.168.1.0	11000000.10101000.00000001.00000000
Netmask:	255.255.255.0	11111111.11111111.11111111.00000000
Wildcard:	0.0.0.255	00000000.00000000.00000000.11111111
Network Address:	192.168.1.0 / 24	11000000.10101000.00000001.00000000
Broadcast Address:	192.168.1.255	11000000.10101000.00000001.11111111
First host:	192.168.1.1	11000000.10101000.00000001.00000001
Last host:	.192.168.1.254	11000000.10101000.00000001.11111110

ROUTER IP CONFIGURATION :

DHCP

Short for Dynamic Host Configuration Protocol, a protocol for assigning dynamic IP addresses to devices on a network.

IP address conflict:

If you defined a static IP address for a network device, duplicate IP address conflicts may occur on a DHCP network

This article is useful those who works in broadband maintenance,networking etc

EL/Super conductivity/SET-2/Paper-01

Q1. Superconductivity is observed for
(a) infrared frequencies
(b) dc and low frequency
(c) AC and high frequency
(d)frequency having no effect

Ans:b
Q2. superconductivity can be destroyed by

(a) adding impurities
(b) reducing temperatures
(c) application of magnetic field
(d) any of the above

Ans:c
Q3. Superconducting metal in superconductivity state has relative permeability of

(a) zero           (b) one              (c) negative              (d) more than one

Ans: a
Q4. The super conductivity is due to

(a) the crystal  structure having no atomic vibration at 0^o K
(b)all electronics interact in the super conducing state
(c)the electronics jump into nucleus at 0^o K
(d) none of those

Ans:a

Q5. The structure sensitive property of a super conductor is
(a) Critical magnetic field
(b) transition temperature
(c) Critical current density
(d) none of the above
Ans:c

Broadband Equipment MCQs Set-2

1. What for Set Top Box is used .

 (a) VOIP       (b) IPTV       (c) VPN       (d) ISDN

2. BNG in Multiplay Network is connected to

   (a) Core Router  (b) PE router  (c) DSLAM  (d) BRAS

3. Triple play Service through Broad band means

   (a)Data, Games and Audio simultaneously
   (b)Data,voice and  Games simultaneously
    (c)Data, voice and video simultaneously
   (d)Voice,Video and Audio simultaneously

4. BNG behaves as _____________________ router in BSNL multiplay

   (a) Core Router  (b) Provider Edge Router (c)Customer Edge Router  (d)Gate way router

5. Voice in Broad band Multiplay is

   (a) Voice over PSTN
   (b )Voice over IP
   (c) Voice over PLMN
   (d) Voice over ISDN

6. Set Top Box interfaces with Television using
   (a) Ethernet Port  (b) Serial Port  (c) 3- RCA cable (d) RS 232 port

_________________________________SOLUTION________________________________
1.b

2.a

PE router
BNG - Broadband Network Gateway
RPR - Tier-I Switch and Tier-2   switches in the ring Provides connectivity to BNG & Vice versa
OCLAN - Tier-2 Swich
DSLAM
ADSL CPE 

3.c

4.c  BNG behaves as Customer Edge Router where as BRAS was a PE router.

5. b BB Multiplay - The triple play service means providing the following service to the customer:

• Data (Ineternet)
• Voice (VoIP and not the PSTN)
• Video (IPTV )

6. c  On one side of  Set Top Box interfaces with the television using the 3-RCA or the S-Video ports, and on the other side it is connected to broadband ADSL modem via the Ethernet port.

Basic Electrical/Electrical circuits/Level-0/Paper-04

Q1. Which of  the following is non-linear  circuit parameter ?

(a)Inductance
(b)Condenser
(c)wire wound resister
(d)Transistor

Q2. A capacitor is generally a

(a) bilateral and active component
(b) active, passive linear and nonlinear component
(c) linear and bilateral component
(d) non-linear and active component

Q3. The circuit whose properties are same in either directions is known as

(a) unilateral circuit
(b) bilateral circuit
(c) irreversible circuit
(d) reversible circuit


Q4. The circuit has resistor, capacitor and semiconductor diode the circuit will be

(a)non linear circuit
(b) linear circuit
(c) bilateral circuit
(d) none of the above

Q5. A network which contains one or more than one source of emf is known as

(a)linear network
(b) non linear network
(c) passive network
(d)active network

______________________________SOLUTIONS________________________________________

A circuit is a closed conducting path through which an electric current either flows or is intended flow.

• Linear circuit is one whose parameters are constant  i.e. they do not change with  voltage or current.

• Non-linear circuit whose parameters change with voltage or current

Q1.a

The various elements of  an electric circuit are called its parameters like resistance,inductance and capacitance . These parameters may be lumped or distributed. 

Q2.c

• Example of passive components : resistor,capacitor,inductor etc
• Example of active components : Diode,Trasistor ,voltage source,current source etc

Q3.b

Unilateral circuit whose properties or characteristics change with the direction of its operation.A diode rectifier is a unilateral circuit , because it cannot perform rectification in both directions.

Q4.a

Q5.d

Passive Network is one in which contains no source of emf in it.

Small Form-factor Pluggable (SFP) Optical Transceivers

A SFP is a hot-swappable input/output device that plugs into the SFP ports, linking the switch with the fiber-optic network.The following SFP media types are supported:

• CWDM (CWDM-SFP-xxxx=)
• Cisco 1000BASE-T SFP (GLC-T=)
• Short wavelength 1000BASE-SX (GLC-SX-MM=)
• Long wavelength/long haul 1000BASE-LX/LH (GLC-LH-SM=)
• Extended distance 1000BASE-ZX (GLC-ZX-SM=)

A small form-factor pluggable (SFP) Gigabit LH40 transceiver that provides a full-duplex Gigabit solution up to 40 km on a single mode fiber.

• 100BASE   -   FE Fast Ethernet
• 1000BASE -   GE Gigabit Ethernet

• Long Haul ( LH ) denotes longer distances 
• Long Wavelength ( LX ) denotes less energy which is  shorter distance

Generally a SFP module is either made for single mode (More distance) / multi-mode (short distance).If used with SM fiber it can go upto 10Km

Inserting and Removing Blade-Clasp SFP module

The blade-clasp SFP module has a blade clasp that you use to secure the SFP module in a switching module port.

Waning :

Invisible laser radiation may be emitted from disconnected fiber or connectors. Do not stare in to beams or view directly with optical instruments.

Inserting a Blade-Clasp Module:

To insert a blade-clasp SFP module into a swiching module port, follow these steps:

 step 1: Close the blade-clasp before inserting the SFP module.

 step 2 : Line up the SFP module with the port, and slide into the port.

Caution:

Protect your SFP modules by inserting clean dust plugs into the SFPs after the cables are extracted from them. Be sure to clean the optic surfaces of the fiber cables before you plug them back into the optical bores of another SFP module. Avoid getting dust and other contaminants into the optical bores of your SFP modules: The optics do not work correctly when obstructed with dust.

Basic Electrical/Capacitance/Set-1/Paper-03

Q1. A consists of two

(a) insulation separated by dielectric (b) conductors separated by an insulator
(c) ceramic plates and one mica disc (d) conductors separated by air medium

Q2.  The capacitance of a capacitor is NOT influenced by

(a) plate thickness     (b)plate area   (c) plate separation    (d)nature of  dielectric

Q3.  A capacitor that stores a charge of 0.5 C at 10 volts has a capacitance of ________

(a) 5           (b)20             (c)10               (d)0.05

Q4. In a capacitor, the electric charges is stored in _________________

(a)metal plate (b)dielectric     (c)both a &b   (d)none of the above

Q5.  In a parallel plate capacitor, if a dielectric slab is introduced, then

(a)potential difference between plate will decrease
(b) electric intensity will decrease
(c) capacitance will increase
(d) all of the above



__________________________________SOLUTION________________________________

Q1. b
Q2. a

Q3.d

 C = 0.5/10 = 0.05 F

Q4.b
Q5.d

Basic Electrical/Resistance/Level-1/Paper-01

Q1. Two wires A and B have the same cross-section and are made of the same material. Ra  =600 ohm ad Rb =100 ohm. The number of times A is longer than B is

 (a) 6               (b)2                         (c) 4              (d)5

Ans: a

Q2. Two copper conductor have same length but one has cross-section twice that of the other. If thicker has a resistance of 20 ohm, the resistance of the other is ____________ohm

(a)10                (b)40                 (c)20                  (d)60

Ans:b

Hint :  A1= 2A2

Q3. Which of the following material has nearly zero temperature coefficient of resistance  ?

 (a)manganin           (b)porcelain        (c)copper                   (d)carbon

Ans:a

Q4. Which of the  following does not have negative temperature coefficient ?

 (a)Paper              ( b)Aluminium                        (c) Rubber                  (d) Mica

Ans: b

Q5. Resistance of a material always decreases if

  (a) temperature of material  is decreased
  (b) temperature of material  is increased
  (c) number of  free electrons available become more
  (d) none of the above is correct

Ans: c

Hysteresis loop or B-H curve

A B-H curve is used to show the relationship  between magnetic flux density (B)  and magnetic filed strength (H) for a material.The area of the hysteresis loop is related to the hysteresis loss.The area of hysteresis loop of a material is large, the hysteresis loss in this material will be large.Narrow hysteresis loops also have high permeability (the slope of B with respect to H) and magnetization.

                                                                 Hysteresis loop or B-H curve

Retentivity is a material's ability to retain a certain amount of residual magnetic field when the magnetizing force is removed after achieving saturation.

Coercive Force : The amount of reverse magnetic field which must be applied to a magnetic material to make the magnetic flux return to zero. 

Non retentive or soft  magnetic materials :

Soft (ferro) magnetic materials have a narrow hysteresis loop and they are easily magnetized. High saturation magnetization and a low coercivity (narrow B-H curve).Non retentive  magnetic materials  having  low magnetic losses and narrow hysteresis loop.

Retentive or hard magnetic materials :

Hard (ferro)  magnetic materials material such as cobalt steel retain their magnetism for long period of time, when  the magnetizing field is removed. i.e. They can act as a permanent magnet .Retentive or  hard  magnetic material  having high coercivity , high losses and large hysteresis loop 

Table 1 :  Narrow Vs Larger hysteresis loop area

Narrow hysteresis loop	Larger hysteresis loop
Soft (Ferro) magnetic    materials, have small coercive force	Hard (ferro) magnetic  materials have large coercive force
Lower - Retentivity,Coercivity, Reluctance, Residual Magnetism	Higher  - Retentivity,Coercivity , Reluctance, Residual Magnetism
Higher - Permeability	Lower - Permeability

                                            

Basic Electrical/Transformer/Page-01

This blog is an attempt to help you familiarize  electrical engineering competitive exam questions and answers.
The standard for the exam will be expect of an engineering holder.
This question paper may include the  following type of questions

• Direct questions contains - direct Theory and definition questions
• Problems - apply Mathematical formula for the solution.
• Advanced level questions include Design & application level questions
• Tricky or twisted question

1. Transformers are rated in

     (a)kV     (b)kW        (c) kWH       (d)KVA

Ans: d

2. The  transformer works on the principle of
     (a) static induction                  (b) self induction           (c) mutual induction    (d) both a and b
Ans: d

3. Transformer is used to change the vales of
          (a) Frequency (b) voltage (c) power (d)power factor
Ans:b

Tips: Transformer is used to change the values of  voltage and current. Transformer does not change the frequency and wave form.

4. A transformer provides a path for magnetic flux of
     (a) high conductivity (b) high reluctance (c) low reluctance (d) low conductivity
Ans:c

5.The emf induced in a coil depends on
    (a) the number of its turns
     (b) the change of flux linked with it
     (c)the time taken to change the flux
    (d)all of the above
Ans: d

Broadband equipments

DSL TECHNOLOGY

•  Digital Subscriber Line (DSL)  uses the same telephone line as traditional  modem
• Provides simultaneous access to Web and Telephone
• DSL remains  always -on all the time
• On power failure , telephone line is still available like a standard telephone line.

DSL Equipment

        DSL uses two pieces of equipment, one on the customer end and one at the telephone Exchange.  At the customer's location there is a DSL modem. The  DSL Access Multiplexer (DSLAM) is to receive customer connections at the Telephone Exchange.

This  UTStarcom DSLAM  consists of a chassis capable of holding up to 5 ADSL line cards and 2 CONTROL CARDs.Each ADSL line card has 48 ADSL ports.

DSLAM  UTSTAR COM  

Preventive maintenance of  DSLAMs

1.      Daily physical checking the Optical Fiber link between DSLAM and RPR .

2.   Perform following checks at least on  DSLAMs  everyday and take necessary action

      if any  card / equipment is found faulty 

a.      Check the status of control card of DSLAM .

b.      Check the status of all Fans in DSLAM.

c.      Check the status of all cards of the DSLAM. 

3. Check the status of all ports of each card in DSLAM and try to reset the hanged ports in DSLAM

4. Cleaning of DSLAM filter whenever required .

The faulty card may be got replaced with a spare card if available immediately 

Do's and Don'ts for broadband customers

Do's 

1. No phone or Fax should be connected before splitter 
2. Check your usages regularly (once in a month)
3. Please clean your computer virus regularly
4. Please swich off the modem when not in use

Don'ts

       Please do not disclosure your broadband User ID and Password to anybody

NETWORK COMPONENTS

BNG - Broadband Network Gateway
RPR - Resilient Packet Ring
DSLAM - Digital Subscriber Line Access Multiplexer
CPE -  Customer Premises Equipment (modem)

DSL Technology multiple choice questions

1. To enable DSL technology  internet service provider must have a ________________ located in their          networks to interact with customer modem
    (a) DSLAM
    (b) RPR
    (c) LAN switch
    (d) None of these

Ans : a

2. DSLAM s are generally aggregated through _______________interface

     (a) FE
     (b) GE
     (c) both FE and GE
     (d) None of these

Ans:c

3. Which of this is the basic feature of DSLAM?
     (a) DSLAM aggregates the digital subscriber line (DSL)
     (b) DSLAM deliver data transmission over existing copper telephone lines
     (c) DSLAM seperate Voice and Data of the subscriber
     (d)All of the above

Ans: d

4. Which of these have supplied equipment for DSLAM in BSNL ?
     (a) UTSTARCOM
     (b) SIEMENS
     (c) HUAWEI
     (d) All of the above
Ans: d

5. Maximum frequency range of a copper pair is in
    (a) kilo Hertz
    (b) Mega Hertz
    (c) Giga Hertz
    (d) Terra Hertz

Ans: b