ECE Free Online Test-1

Twelve 1Ω resistances are used as edges to form a cube. The resistance between two diagonally oppositive corners of the cube is?

A.6/5
B. 1
C. 3/2
D. 5/6

The voltage phasor of circuit is 20 ˪300 V and the current phasor is 4 ˪-300 V. the active and reactive power in the circuit are ( in W & VAR)?

80, 69.28
40, 69.28
80, 34.64
40, 34.64

R=2KΩ, L=2H, C= 2uF are connected in parallel. What is the 3-dB bandwidth?

250
500
750
1000

R=2KΩ, L=2H, C= 2uF are connected in parallel. What is the resonance frequency?

250
500
750
1000

Diffusion is associated with random motion of electrons or holes due to?

External applied electric field
Concentration gradient of electrons or holes
Thermal agitation
None

Electrons or holes are drifted in one direction due to?

External applied electric field
concentration gradient of electrons or holes
Thermal agitation
None

Doped Si at 300K contains 1016 acceptor atom/cm3. ni= 1.5*1010cm-3. Then what is the hole concentration?

(10)16 cm-3
1.5*(10)16 cm-3
2.25*(10)4 cm-3
(10)4 cm-3

in optical fiber communication what is the range of "S" band?

1260-1360
1360-1460
1460-1530
1530-1565

optical fiber communication used spectrual band rang (nm)?

800-1250
1250-1860
800-1675
800-1575

the message signal contain 3 signals. those are 5, 10, 20 KHZ's. then the bandwidth of AM is (in KHZ)?

10
20
30
40

Show me the answers!

Question 1: The correct answer is the :  5/6

Question 2: The correct answer is          40W, 69.28VAR

Question 3: The correct answer is         250

Question 4: The correct answer is        500

Question 5: The correct answer is        B & C

Question 6: The correct answer is        External applied electric field

Question 7: The correct answer is       (10)16 cm-3

Question 8: The correct answer is        1460-1530

Question 9: The correct answer is        800-1675

Question 10: The correct answer is       40.

You answered them all right!