PHY301 Final Term Past Paper 2005

FINAL TERM EXAMINATION · SEMESTER (Spring 2005)I · PHY-301 CIRCUIT THEORY · Instructions

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

ID · Exam Center · 21-07-2005

**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.

Question Total Signature Marks

Q1. Marks: 5

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

Q1. The resistance in a short circuit is

1. Large
2. small
3. Zero
4. 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

Q3. The charge in motion is called

1. Voltage
2. current
3. intensity
4. Coulomb

Q4. The emitter current is always

1. Greater than base current
2. Less than collector current
3. Greater than collector current
4. Small than base current

Q5. In PNP transistor, the P-regions are

1. Base and emitter
2. Base and collector
3. emitter and collector
4. All of the above

Q2. Marks: 15

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 Ω 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.

Q3. Marks: 15

Using superposition find

a) the current through the -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.

Q4. Marks: 5

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.