 # Electronics Engineering Mastery Test 11: ECE Pre-Board

(Last Updated On: March 22, 2018) This is 100 items set of Practice Examination 11 in Electronics Engineering composed of previous and/or poterntial Board Exams Questions. Read each questions and choices carefully! Choose the best answer. In the actual board, you have to answer 100 items in Electronics Engineering within 5 hours. You have to get at least 70% to pass the subject. Electronics Engineering is 30% of the total 100% Board Rating along with Mathematics (20%), General Engineering and Applied Sciences (20%) and Electronics Systems and Technology (30%).

### Start the Test Yourself Exam 11

Choose the letter of the best answer in each questions.

1. A power derating factor of 3.33 mW/°C above 50°C means that

• A. you must decrease the DC power dissipation rating by 3.33 mW for every 1°C rise in the operating temperature above 50°C
• B. you will end up getting a power of 3.33 mW if temperature goes beyond 50°C
• C. you must increase the DC power dissipation rating by 3.33 mW for every 1°C rise in the operating temperature above 50°C
• D. your zener diode will dissipate a nominal DC power of 3.33 mW for temperature above 50°C

Solution:

2. When you first turn a power supply on, the filter capacitor initially acts as a short circuit thus creating a high initial current that can possibly destroy your rectifier diodes. What is the best way to limit the said current but without sacrificing the output voltage?

• A. use a large-value series current-limiting resistor
• B. use large-value filter capacitors
• C. use inductive filters instead of capacitive filters
• D. don’t turn off your power supply

Solution:

3. The electromagnetic force induced between a varying magnetic field and a stationary conductor.

• A. Mutually induced EMF
• B. Self-induced EMF
• C. Electro statically induced EMF
• D. Statically induced EMF

Solution:

4. A wire has a resistance of 5 Ω at room temperature and a temperature coefficient α = 4 × 10-3/°C. Calculate the wire resistance if the temperature rises by 75°C.

• A. 6.5 Ω
• B. 6.1 Ω
• C. 6 Ω
• D. 6.16 Ω

Solution:

5. A combination of two charges with equal charge magnitude but opposite signs.

• A. magnetic dipole
• B. static dipole
• C. dynamic dipole
• D. electric dipole

Solution:

6. If a dc electromagnetic of 10-V produces a steady-state current of 100-mA in a 100 Ω coil, how much will the current be after 0.2 sec?

• A. 63 mA
• B. 100 mA
• C. 37 mA
• D. 200 Ma

Solution:

7. What is the time constant of a 20-H coil having 100 Ω of series resistance?

• A. 5 s
• B. 0.5 s
• C. 0.2 s
• D. 20 ms

Solution:

8. If the RC time constant is given to be 1 s, how long will it take for the voltage to drop from 100 V to 50 V?

• A. 0.63 s
• B. 0.37 s
• C. 0.5 s
• D. 0.7 s

Solution:

9. The effect of little change in magnetic flux density when magnetic field intensity increases.

• A. Retentivity
• B. Coercivity
• C. Saturation
• D. Permeability

Solution:

10. A series resonant circuit at 0.2 MHz develops 100 mV across a 250 µH coil with a 2 mV input. Calculate Q.

• A. 50
• B. 25
• C. 100
• D. 200

Solution:

11. A point in magnet where the intensity of magnetic lines of force is a maximum.

• A. North Pole
• B. Saturation Point
• C. Coercive point
• D. Magnetic pole

Solution:

12. An oscillator circuit that has two capacitors and one inductor on its feedback network

• A. Colpitts
• B. Clapp
• C. Hartley
• D. Pierce Crystal

Solution:

13. The ability of a substance of getting magnetized is called

• A. Retentivity
• B. Permeability
• C. Coercivity
• D. Susceptibility

Solution:

14. A 12 volt battery is connected to a 5 cm, 350 turn coil with resistance of 15-Ω. What is the field strength produced in Oe?

• A. 70
• B. 280
• C. 56
• D. 353

Solution:

15. A magnetic material has a relative permeability of 500. What is the absolute permeability of the material in cgs system?

• A. 500
• B. 630 H/m
• C. 500 G/Oe
• D. 630 x 10-6 G/Oe

Solution:

16. The reciprocal of reluctance corresponds to what in electric circuits?

• A. Permeance
• C. Impedance
• D. Conductance

Solution:

17. A material with negative temperature coefficient means

• A. Its resistance will increase as temperature increases
• B. Its resistance will decrease as temperature decreases
• C. Its resistance will increase as temperature decreases
• D. Its resistance will decrease as temperature increases

Solution:

18. A 12-V battery with a capacity of 100 A-hr is used to supply 300-W electronic equipment and a 25 W light. How long will this battery last?

• A. 7.38 hours
• B. 3.69 hours
• C. 5.22 hours
• D. 2.61 hours

Solution:

19. The physical motion that is due to the forces of magnetic fields

• A. Repulsion
• B. Attraction
• C. Motor Action
• D. Rotation

Solution:

20. Which of these statements is FALSE about the relationship of the magnetic force on a moving charge?

• A. A magnetic force does not point in the direction of the field or in the direction of the charge’s velocity
• B. A magnetic force is exerted on a moving electric charge
• C. No magnetic force is exerted on a charge at rest
• D. A magnetic force is exerted on a charge moving along the direction of the magnetic field

Solution:

21. Indicate which of the following statements is FALSE.

• A. Capacitive reactance is a measure of the reaction of C to a change in voltage
• B. RC time constant is a measure of the reaction of C to a change in voltage
• C. The concept of reactance is useful for both sine wave AC circuits and non-sinusoidal waveforms
• D. The method of time constant is used to analyze both sinusoidal and non-sinusoidal waveforms

Solution:

22. It is the ability of an insulator to concentrate electric flux

• A. Permeability
• B. Susceptibility
• C. Permittivity
• D. Retentivity

Solution:

23. It is commonly used for precision wire-wound resistors, which do not change resistance when the temperature increases

• A. carbon
• B. aluminum
• C. constantan
• D. iron

Solution:

24. Which of the following statements is true about the force on a current-carrying straight conductor in a magnetic field?

• A. With the conductor at 90°, the reaction between two magnetic fields is minimum
• B. With the conductor at 0°, there is no effect between them
• C. With the conductor is at angle between 0° and 90°, only the parallel component is effective
• D. A motor action can be produced if the conductor is placed parallel to the magnetic field

Solution:

25. It is known as the breakdown voltage of a dielectric material.

• A. relative permittivity
• B. dielectric strength
• C. velocity reduction ratio
• D. velocity factor

Solution:

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