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MID TERM EXAMINATION

SEMESTER Fall (2004)I PHY- 301 CIRCUIT THEORY

Total Marks: 50

Duration: 60 min

Maximum Time Allowed: (1 Hour)

Instructions Please read the following instructions carefully before attempting any question:

All questions are compulsory.

a. This exam consists of One Multiple Choice Questions (MCQ's) ,which carries 5 Marks

and four descriptive questions.

b. Each MCQ carries 1 Marks.

c. While attempting descriptive question do not miss any step so that you could get

better marks.

d. Do not ask about the contents of any question of this examination from anyone.

e. If you think that there is something wrong with any of the questions, attempt it to

the best of your understanding.

f. On the other hand, if you believe that all of the choices provided for a particular

question are the wrong ones, select the one that appears to you as being the least

wrong.

g. The duration of this examination is 60 minutes.

h. This examination is closed book, closed notes, closed neighbors.

i. Do not ask any questions about the contents of this examination from anyone.

j. Draw Circuit diagrams (where necessary) for each step to get maximum score in the

exam.

**WARNING: Please note that Virtual University takes serious note of unfair means.

Anyone found involved in cheating will be given grade `F` in this course.

For Teacher’s use only

Question Q1 Q2 Q3 Q4 Q5 Total Signature Marks

Question No: 1 Marks: 5

For each question given below, encircle the option that in your opinion represents the best/ correct answer. I) When placed close together, a positively charged material and a negatively charged material will

a) Repel b) Become neutral c) Attract d) Exchange charges

II) Potential difference is another term for

a) Energy b) Voltage c) Watt d) Distance of an electron from the nucleus.

III) There is no current in the circuit when

a) A switch is closed b) A switch is open c) There is no voltage d) Answer (a) and (c) e) Answer (b) and (c)

IV) How much resistance is required to limit the current from a 10V battery to 1mA

a) 100Ω b) 1.0 k Ω c) 10 Ω d) 10k Ω

V) Which of the following statements are true concerning the figure below a) R1 and R2 are in series with R3 , R4, and R5

b) R1 and R2 are in series c) R3 , R4, and R5 are in parallel d) The series combination of R1 and R2 ιs in parallel with the series combination of R3 , R4, and R5. e) Answers (b) and (d)


Use nodal analysis to find IO in the given network.. Identify and label each node otherwise you will lose your marks. Label circuit diagram properly.

Answer/Solution

We will redraw figure as

At Node 3 V3 = -6V

KCL at Node 1 (V1 + 6)/6 + (V1-V2)/6 =-5mA ------ (A)

KCL at Node 2 (V2 + 6)/6 + (V2-V1)/6 + V2/6= 0 ------- (B)

Solving (A) and (B) we get V2=12/5 = 2.4

Now Io = V2/R =2.4/6 =.4 mA


Use Mesh analysis to find currents through all Meshes. Identify and label each mesh otherwise you will lose your marks. Label circuit diagram properly.

Answer/Solution

We will redraw figure as

KVL equation for mesh 1

2+4 I 0 +3 (I -I =1 1 2) 7I1-3I2= -2 -------------------- (1)

Now we will redraw figure for super mesh as

KVL equation for super mesh

1(I 6+3(I =0 -I ) +8I +5I + - I )2 4 3 2 2 1 Simplifying above equation we get

-3I1+9I2+8I3-I4= -6…………….. (2)

KVL equation for Mesh 4

2I +5+3I4+1(I4-I2) =0 4

Simplifying we get -I2+ 6I4= -5…………… (3)

Constraint Equation I3-I2=7 ………….. (4)

From Equation (1) I1= (3I2-2)/7

From Equation (3) I4= (I2-5)/6

From Equation (4) I3=I2+7

Putting the values of I1, I3, I4 in equation (2) & simplifying we get 653I2=-2176

I2= -3.33A I1 = - 1.71A I3 =3.67A I4 =-1.38A


Find the power absorbed by the 30kΩ resistor in the circuit below.

Answer/Solution

Writing KVL equation

-12 -30I + 2Vx+ Vx=0

-12+30kI+20kI+10kI=0 I =200µA

Therefore

P30k=I2*R = (200x 10-6)2*30

= 1.2MW


(a) Two resistors R1 and R2 of 5Ω each and R3 of 10 Ω are in series. How much is RT. If we applied 80 V source across the series string, how much is the current in R3. Answer/Solution

RT = R1+R2+R3 = 5+5+10 = 20Ω

I = VT/RT = 80/ 20 = 4A

(b) Define Potential difference. What is Conventional Current? Answer/Solution Potential difference The potential difference is defined as the amount of work per charge needed to move electric charge from the second point to the first, or equivalently, the amount of work that unit charge flowing from the first point to the second can perform. In the SI system of units, potential difference, electrical potential and electromotive force are measured in volts, leading to the commonly used term voltage and the symbol V.

OR

Current flowing in a conductor is due to a potential difference between its ends. Electrons move from a point of less positive potential to more positive potential and the current flows in the opposite direction. The SI unit of potential difference is the volt (V).

Volts are the measure of Potential Difference across circuit elements (battery, resistor etc.).

Conventional Current The motion of positive charge, in the opposite direction from electron flow, is considered as conventional current. Electricity was known of long before Benjamin Franklin. It was not understood very well, but it was known of. Scientists knew there were two kinds of electric charge. They knew there was electric current. Scientists believed that the opposite charges moved similarly in opposite directions. They defined one as positive and one as negative. They defined current to be in the direction of the positive charges. Later, they learned of their mistake. Only the negative charges move freely in conductors. Electrons had been defined as the negative charges. Current had been defined "backwards". It was too late to redefine all of electrical physics, so the inconvenience holds to this day. The direction that the electrons move is opposite the direction that current points. Because of how electricity works, it isn't much of a problem. Negative charge moving to the left through a wire has the same effect as positive charge moving to the right. So long as the total charge in the wire (protons and electrons) remains balanced, no trouble occurs.


FINAL TERM EXAMINATION SEMESTER (Fall 2004)

PHY-301 CIRCUIT THEORY

Total Marks: 50 Duration: 120min

Student ID/Login ID

Name

PVC Name/Code

Exam Center

Date 11-02-2005

Instructions


Please read the following instructions carefully bM

CQ carries 1 Marks .


better marks.




g. On the other hand, if you believe that all of the choices provided for a particular


wrong.

h. The duration of this examination is 120 minutes.

i. This examination is closed book, closed notes, closed neighbors.

j. Do not ask any questions about the contents of this examination from anyone.

k. Draw Circuit diagrams (where necessary) for each step.

**WARNING: Please note that Virtual University takes serious note of unfair means. Anyone found involved in cheating will be given grade `F` in this course.

For Teacher’s use only Question Q1 Q2 Q3 Q4 Q5 Total Signature Marks


For each question given below, encircle the option that in your opinion represents the best/ correct answer.

I) Choose the correct term, an electronic device that is capable of storing a charge for a long time. a) Transistor b) Semi-conductor c) Capacitor d) Diode

II) The unit of electrical potential difference is a) watt b) Volt c) ohm d) ampere

III) Resistances R1 and R2 are in series with 90 V applied. If V1 is 30 V then V2 must be a) 30 V b) 90 V c) 45 V d) 60 V

IV) In an N –type semiconductor materials, the majority carrier are a) Holes b) Electrons c) Ions

d) Protons V) When a current of 20 milliamps flows through a 50 ohm resistor the voltage drop across the resistor will be:

a) 100 mill volts b) 10 mill volts c) 1 volt d) 10 volts


Use Mesh analysis to find currents through all Meshes. Label circuit diagram properly. Write each step of the calculation to get maximum marks.


Find Vo in the network using Source Transformation. Draw and label the circuit diagram of each step, otherwise you will lose your marks. Write each step of calculation to get maximum marks.


a) How does transistor work? b) What is PN-junction diode.


The transistor in the circuit below has a very high β. Find VE and VC for VB (a) +6V, (b) +2V, and (c) 0V. Assume VBE ≅ 0.7 V.

PHY301 Final Paper Page 1 of 4

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PHY301 Circuit Theory Final Term Examination - July 2003

Session -1

TIME ALLOWED: 150 Minutes TOTAL MARKS: 66 Please read the following instructions carefully before attempting any of the questions:

a. All questions are compulsory. b. This exam consists of 10 Multiple Choice Questions (MCQ's); one question is for filling in the

blanks which carries 20 Marks and three descriptive questions. c. Each MCQ carries 1 Marks. d. Fill in the blanks question carries 20 Marks. e. While attempting descriptive question do not miss any step so that you could get better marks. f. You can type the answer of descriptive question in Ms Word and then copy it in the software

provided to you by the Virtual University. All the figures and formats should also be made in the Ms Word and then be copied in the provided software. For figures you can use MS PAINT.

g. When you have copied your answer in the software. Do not worry if it's format changes. h. Save your answer before proceeding to the next question. i. Do not ask about the contents of any question of this examination from anyone. j. If you think that there is something wrong with any of the questions, attempt it to the best of

your understanding. k. On the other hand, if you believe that all of the choices provided for a particular question are

the wrong ones, select the one that appears to you as being the least wrong. l. Do not click the "Finish" button" while solving your paper. Once you clicked the "finish" button,

you will not be able to access your paper again. Click it at the end of your paper. That means you have submitted your complete paper.

Total Questions 14

Q.No 1 International system of units is built upon how many basic units.

o 8 o 9 o 10 o 7

Q.No 2 Absolute zero corresponds to

o 0oC

o 32oC o 273K o 0 K

Q.No 3

Two unlike charges will o Attract o Repel o None of the above

Q.No 4

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With zero potential difference across a wire, the current will be o Maximum o Depends upon the wire o Zero o None of the above

Q.No 5

The opposition which limits the current is called o Conductance o Resistance o Resistivity o Conductivity

Q.No 6

In the above circuit value of Io will be o 2mA o 1A o 2A o 1mA

Q.No 7

The process whereby charged particles move under the influence of electric field is called

o Current o Voltage o Drift o None of the above

Q.No 8 Phosphorus is a -------- element

o Pentavalent o Trivalent o Hexavalent o None of the above

Q.No 9

The current flows through the diode when it is reverse biased is called o Leakage current o Breakdown current o Saturation current o None of the above

Q.No 10 The resistance offered by the inductor is called

o Inductance o Capacitance o Resistivity o None of the above

Q.No 11

Fill in the blanks.


All questions carry 2 marks each (i) Mole is a unit of ------------ (ii) 1 Mega Ohm is equal to ----------- ohms. (iii) Hydrogen has an atomic no ---------------. (iv) Electron valance is the no of electron in the incomplete -------- shell. (v) The voltage drop across a short circuit is --------- . (vi) The current that results from the diffusion of charged particles is called -------

current. (vii) Doped silicon in which majority of charge carriers are negatively charged

electrons is called ---------- type. (viii) The windings of transformer connected to the load is called ---------windings. (ix) One diode can be used as a ------- wave rectifier. (x) Analyze the following circuit

Req = --------------. Q.No 12

Carry out analysis of the circuit to calculate voltage at all nodes and current through all branches. Please show all steps for the calculation. [20]

Q.No 13

(a) Find the resultant inductance of the circuit. Please show all steps for the calculation.

(b) Define the following sources [4] (i) Independent voltage source. (ii) Voltage dependent current source.

Q.No 14

Calculate the current through the circuit. Please show all steps for the calculation. [10]


Student ID/Login

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Exam Center

Date 21-07-2005

FINAL TERM EXAMINATION

SEMESTER (Spring 2005)I PHY-301 CIRCUIT THEORY

Total Marks: 50

Duration: 120min




a. This exam consists of One Multiple Choice Questions (MCQ's) ,which carries 5 Marks

and four descriptive questions.

b. Each MCQ carries 1 Marks .


better marks.




f. On the other hand, if you believe that all of the choices provided for a particular


wrong.

g. The duration of this examination is 120 minutes.

h. This examination is closed book, closed notes, closed neighbors.

i. Do not ask any questions about the contents of this examination from anyone.

j. Draw Circuit diagrams (where necessary) for each step.



Question Q1 Q2 Q3 Q4 Q5 Total Signature

Marks


For each question given below, encircle the option that in your opinion represents the best/ correct answer.

1)The resistance in a short circuit is a) Large b) small c) Zero d) None of the above

2) If one of the diode in a full –wave bridge rectifier is open, the out put is a) 0V b) One –fourth the amplitude of the input voltage c) a half –wave rectified voltage d) a 120 HZ voltage

3) The charge in motion is called a) Voltage b) current c) intensity d) Coulomb

4) The emitter current is always a) Greater than base current b) Less than collector current c) Greater than collector current d) Small than base current

5) In PNP transistor, the P-regions are a) Base and emitter b) Base and collector c) emitter and collector d) All of the above


For the circuit shown in the figure below, all the resistors are given in Ohms; (a) Find the equivalent resistance seen by the supply (b) Find the power in the source and the 10Ω resistor. Draw the circuit diagram of each step otherwise you will lose your marks. Write each step of the calculation to get maximum marks and also mention the units of each derived value.


Using superposition find

a) the current through the 3-Ω resistor due to the voltage source b) the current through the 3-Ω resistor due to the current source c) the power delivered to the 3-Ω resistor

Draw and label the circuit diagram, otherwise you will lose your marks. Write each step of calculation and also mention the units of each derived value.


What is tunnel diode? Draw the graphic symbol of tunnel diode. Describe the negative resistance operating region of the tunnel diode. Include the relationship between diode forward current and forward voltage.


For the NPN bipolar transistor, assume that the VBE(on) = 0.7V. (a) If VCC = 5V, solve for IB, IC, and IE. Assume that β = 100. Be sure to justify each step that you take. (b) Resolve this using β=200 Be sure to justify each step that you take, also mention the units of each derived

value

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MID TERM EXAMINATION MID TERM EXAMINATION

SEMESTER (Summer 2007) I SEMESTER (Summer 2007) I

PHY- 301 CIRCUIT THEORY PHY- 301 CIRCUIT THEORY

Total Marks: 40 Total Marks: 40

Duration: 120 min Duration: 120 min




¾ This exam consists of One Multiple Choice Questions (MCQ's) ,which carries 6 Marks

and three descriptive questions.

¾ While attempting descriptive question do not miss any step so that you could get

better marks.

¾ If you think that there is something wrong with any of the questions, attempt it to


¾ On the other hand, if you believe that all of the choices provided for a particular


wrong.

¾ This examination is closed book, closed notes and closed neighbors.

¾ Do not ask any question about the contents of this examination from anyone.

¾ Draw Circuit diagrams (where necessary) for each step to get maximum score in

the exam.


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Question Q1 Q2 Q3 Q4 Total Signature Marks


For each question given below, encircle the option that in your opinion represents the best/ correct answer. Encircle only “ONE” option. I) Current divider is used when

a) two or more resistances are in series to a voltage source b) two or more resistances are in parallel to a current source c) One resistance in parallel to current source d) None of above

II) 10Ω and 5Ω resistances are in series. If current through 5Ω is 5 ampere , current of 10Ω will be a) 10A b) 20A c) 5A d) 40

III) If the current arrow is directed into the + marked terminal of an element, then p=vi yields the………………...

a) absorbed power b) emitted power c) loss power d) high power

IV) When a proton and an electron come close together they a) repel each other b) become neutral c) have no effect d) attract each other

V) The resistance of an open circuit is a) high b) low c) zero d) infinite

VI) The current passing through the conductor is directly proportional to the voltage provided temperature remains constant, is the statement of

a) Kirchhoff’s law b) Newton’s law c) Ohm’s law d) Pascal law


(a) Why does a person wearing rubber shoes do not get electric shock when touching a naked conducting wire.

Marks=3 (b) Find voltage across 20kΩ in the figure below.

Marks =5 Question No: 3 Marks: 14

Use nodal analysis to find VO in the network given below. Identify and label each node otherwise you will lose your marks. Write each step of the calculation to get maximum marks and also mention the units of each derived value.


Use Mesh analysis to find Current through each mesh in the given network. Identify and label each mesh and also show each step of calculation otherwise you will lose your marks and also mention the units of each derived value. .


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Students FINALTERM EXAMINATION

SPRING 2006

PHY301 - CIRCUIT THEORY (Session - 1 )

Marks: 60

Time: 120min

StudentID/LoginID:

Student Name:

Center Name/Code:

Exam Date: Saturday, August 19, 2006

Instructions

Please read the following instructions carefully before attempting any question:


¾ This exam consists of One Multiple Choice Questions (MCQ's) ,which

carries 10 Marks and four descriptive questions.

¾ While attempting descriptive question do not miss any step so that you

could get better marks.

¾ Do not ask about the contents of any question of this examination from

anyone.

¾ This examination is closed book, closed notes and closed neighbors.

¾ Do not ask any question about the contents of this examination from

anyone.

¾ Draw Circuit diagrams (where necessary) for each step to get

maximum score in the exam.


For Teacher's use only Question 1 2 3 4 5 6 7 8 9 10 Total

Marks

Question 11 12 13 14


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Marks

Question No: 1 ( Marks: 1 ) - Please choose one Superposition theorem can be applied only to circuit having …….. elements.

Non-linear

Passive

Linear bilateral

Resistive

Question No: 2 ( Marks: 1 ) - Please choose one The output of a half wave rectifier is suitable only for ..........

Running car diodes

Charging batteries

Diode rating

Purity of power output

Question No: 3 ( Marks: 1 ) - Please choose one While calculating Rth current sources in the circuit are

Replaced by opens

Replaced indirect voltage

Replaced by short

Replaced DC voltage

Question No: 4 ( Marks: 1 ) - Please choose one

In parallel circuits all components must

have the same value


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have same potential difference

carry the same current

be switched ON & OFF simultaneously


The clipping level is primarily determined by

shape of the input waveform

value of the resistor

battery voltage

knee voltage of the diode


The depletion region of a P-N junction is formed

During the manufacturing

When forward bias is applied to it

Under reverse bias

When its temperature is reduced


The dc load line of a transistor can be drawn if we know its cut off and ……. points

active

saturation


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quiescent

None of them

Question No: 8 ( Marks: 1 ) - Please choose one The filter is simply a capacitor connected in ----------- with the load resistance.

series

parallel

we can use it in series as well as in parallel

none of them

Question No: 9 ( Marks: 1 ) - Please choose one Zener diode is operated in the ……. Region

cut-off

forward

breakdown

saturation


A tunnel diode is always biased

By dc source

In the reverse direction


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In the middle of its negative resistance region

None of them

Question No: 11 ( Marks: 15 ) Use nodal analysis to find out the power supplied by current source in the network given below. Identify and label each node otherwise you will lose your marks. Write each step of the calculation to get maximum marks and also mention the units of each derived value.

Question No: 12 ( Marks: 10 ) Find VO in the network given below using Thevenin’s theorem. Show each step of calculation otherwise you will lose your marks. Draw and label the circuit diagram of each step and also mention the units of each derived value.

Question No: 13 ( Marks: 10 )

Find IO in the network given below using Norton’s theorem. Show each step of calculation otherwise you will lose your marks. Draw and label the circuit diagram of each step and also mention the units of each derived value.


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Question No: 14 ( Marks: 15 )

(a) Measurement on the circuit below produces labeled voltages as indicated. Find the value of β for the given circuit. Marks=6

(b) For the circuit shown in the figure below, find the emitter, base, and collector voltages and currents. Use β= 32, but assume |VBE| = 0.7V independent of current level. Marks: 9

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Phy301 Collection of Old Papers

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