Elecs And Geas Questions - Ece Quiz Bee

Mathematics

Q1: Which law states that the rate at which an object cools is proportional to the temperature difference between the object and its surroundings, provided that the temperature difference is not too large A1:

Newton’s Law of Cooling

Reference: Algebra and Trigonometry by Stewart p. 416 Q2:

A rectangular page is to contain 24 square inches of print. The margins at the top and bottom of the page are to be 1.5 inches, and the margins on the left and right are to be 1 inch. What should the dimensions of the page be so that the least amount of paper is used?

A2:

9 in x 6 in

Solution:

A = (x+3)(y+2) and xy = 24 A = (x+3)(24/x + 2) = 30 +2x + (72/x) dA/dx = 2 – (72/x2) = 0 x=6 y = 24/6 = 4 (6+3) in x (4+2) in 9 in x 6 in

Reference: Calculus by Larson p. 257 Q3:

Find the arc length of the graph of y = (x 3/6) + (1/2x) on the interval [0.5 , 2]

A3:

33/16

Solution:

[ ( )]

dy 3 x2 1 1 = – =0.5 x2 − 2 2 dx 6 2x x

( )( )

Prepared by: Jeremy Lorenzo T. Virata

1 ) 2 x 0.5( ¿) ¿ ¿2 ¿ 1+¿ √¿ 2 2 dy 1+ =∫ ¿ dx 0.5 x 2−(

S=

2

∫ 0.5

√

( )

Reference: Calculus by Larson p. 531 Q4:

The German mathematician who attributed the modern definition of the term “function” in Calculus

A4:

Peter Dirichlet

Reference: Calculus by Larson p. 71 Q5: Find the equation of sphere that has the points (5, -2, 3) and (0, 4, -3) as endpoints of a diameter 2

A5:

5 ( 2 97 + y−1 ) + z 2= 2 4

( ) x−

Solution:

5 =( , 1, 0 ) ( 5+02 , −2+2 4 , 3−3 ) 2 2 r=

√(

0−

5 2 97 + ( 4−1 )2+ (−3−0 )2= √ 2 2

)

5 2 ( 2 97 + y−1 ) + z 2= 2 4

( ) x−

*Midpoint Formula

*Distance Formula

*Equation of Sphere

Reference: Calculus by Larson p. 832 Q6:

A 20-foot chain weighing 5 pounds per foot is lying coiled on the ground. How much work is required to raise one end of the chain to a height of 20 feet so that it is fully extended?

A6:

1000 ft.lb 20

Solution:

W=

∫ 5 ydy=1000 ft . lb

0.05

Prepared by: Jeremy Lorenzo T. Virata

Reference: Calculus by Larson p. 545 Q7:

The odds that A can solve a given problem are 5 to 7, and the odds that B can solve it are 3 to 6. Find the probability that either A and B can solve the problem.

A7:

¾

Solution:

Odd A = 5/7; PA = 5/5+7 = 5/12 Odd B = 3/6 ; PB = 3/6+3 = 3/9 P(AorB) = 5/12 + 3/9 = 3/4

Reference: Engineering Mathematics by Banzuelo p. 220 Q8:

The dihedral angle of a spherical wedge is 40°, find the volume in cm 3 if its diameter is 7 cm.

A8:

19.95 cm3

Solution:

2 2 7 V = R3 θ= 3 3 2

3

=19.95 c m ( ) ( 40∗π 180 )

3

Reference: Engineering Mathematics by Banzuelo p. 322 Q9:

Find the value of logj(-5)

A9:

2 – j1.0246

Solution:

log j (−5 )=

log (−5 ) log ( 5 )+ log (−1 ) log (5 )+ log ( e jπ ) = = jπ log ( j ) log ( j ) log e 2

( )

= 2 – j1.0246 Reference: Engineering Mathematics by Banzuelo p. 608

e x , e2 x ¿ e 3 x

Q10: Find the Wronskian function of A10: 2 e 6 x

Solution:

[

]

ex e2 x e3 x detA =det e x 2 e 2 x 3 e3 x =2 e 6 x e x 4 e2 x 9 e 3 x

Reference: Engineering Mathematics by Banzuelo p. 559

Prepared by: Jeremy Lorenzo T. Virata

ESAT

Q1:

In Fiber Optics, what type of light source the use organic dyes enclosed in glass tube for an active medium?

A1:

Liquid Laser

Reference: Communications Engineering Reviewer by Balbin p. 280 Q2:

EIRP stands for

A2:

Effective Isotropic Radiated Power

Reference: Communications Engineering Reviewer by Balbin p. 164 Q3:

It refers to a network connection used to carry traffic to and from LANs located in various buildings on campus

A3:

Campus backbone

Reference: Electronic Communication Systems by Tomasi p.867 Q4:

A type of bend that occurs as a result of differences in the thermal contraction rates between the core and the cladding material of an optical fiber.

A4:

Microbending

Reference: Electronic Communication Systems by Tomasi p.582 Q5:

It is a form of AM modulation in which the carrier and one complete sideband are transmitted, but only part of the second sideband is transmitted.

A5:

Vestigial Sideband (VSB)

Reference: Electronic Communication Systems by Tomasi p.217 Q6:

It is a name given to the area between the ceiling and the roof in a singlestory building or between the ceiling and the floor of the next higher level in a multistory building.

A6:

Plenum

Reference: Electronic Communication Systems by Tomasi p.217

Prepared by: Jeremy Lorenzo T. Virata

Q7:

Determine the physical length for a quarter wavelength transformer that is used to match a section of RG-8A/U to a 150Ω resistive load. The frequency of operation is 150 MHz.

A7:

0.5 m 8

Solution:

λ c 3 ×1 0 m/s = = =0.5 m 4 4 f 4 ×150 MHz

Reference: Electronic Communication Systems by Tomasi p.548 Q8:

It refers to the overall intensity of illumination which determines background level in the reproduced image

A8:

Brightness

Reference: Communications Engineering Reviewer by Balbin p. 83 Q9:

The most common type of balun

A9:

narrowband balun / choke / sleeve / bazooka

Reference: Electronic Communication Systems by Tomasi p.516 Q10: The simplest form of tuned-circuit frequency discriminator A10: Slope Detector Reference: Electronic Communication Systems by Tomasi p.310 Q11: Actual user information conveyed through the satellite system A11: Payload Reference: Communications Engineering Reviewer by Balbin p. 247 Q12: What is the speed of sound if the temperature is 45°C? A12: 362.82 m/s Solution:

v =331.45+0.697 ( T ) =331.45+0.697 ( 45 )=362.82 m/ s

Q13: It is the tendency for the sound to persist over a definite period of time after it has been produced originally and stopped at the sources. A13: Reverberation Reference: Communications Engineering Reviewer by Balbin p. 247

Prepared by: Jeremy Lorenzo T. Virata

Q14: What is the grade of service if there are 5 trunks used considering traffic of 4.52 erlang? A14: 0.2 Solution:

GOS=¿

Q15: What do you call the farthest point in an orbit of planet Mars? A15: Apoareion Reference: Electronic Systems and Technologies by Allado and Tuvida p. 326 Q16: A non-inductive power resistor used to simulate an antenna A16: Dummy / Dummy Load Reference: Electronic Systems and Technologies by Allado and Tuvida p. 108 Q17: It refers to the changing of the time order of digital information before transmission to reduce the effect of burst errors in the channel. A17: Interleaving

Q18: A silica fiber has measured losses of 2dB/km at 0.9mm. If a total fiber loss of 25dB can be tolerated in a single sink, determine the appropriate repeater spacing A18: 12.5 km Solution:

Z=

Amax 25 dB = =12.5 km A 2 dB /km

Q19: Determine the gain of a 6ft. parabolic dish operating at 1800 MHz A19: 28.59dB

Solution:

G(db) =

[ ( )]

10 log 6

D λ

2

[(

=10 log 6

6 9.84 ×108 1800× 106

)] 2

= 28.59dB

Reference: Communications Engineering Reviewer by Balbin p. 175

Prepared by: Jeremy Lorenzo T. Virata

Q20: Refers to unwanted sum intermodulation distortion

and

difference

frequencies

generated

by

A20: Cross products Reference: Electronic Communication Systems by Tomasi p.27

Prepared by: Jeremy Lorenzo T. Virata