MCQOPTIONS
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MCQOPTIONS
This section includes 151 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
The output phase for a transformer is: |
| A. | in phase with the input |
| B. | out of phase with the input |
| C. | dependent on the direction of the primary and secondary windings |
| D. | dependent on the frequency of the primary source |
| Answer» D. dependent on the frequency of the primary source | |
| 102. |
Opposition to current flow without the dissipation of energy is called: |
| A. | resistance |
| B. | inductive reactance |
| C. | counter emf |
| D. | impedance |
| Answer» C. counter emf | |
| 103. |
A loaded transformer will achieve mutual induction when: |
| A. | secondary current increase causes a primary current decrease |
| B. | primary current is increased by an increase in secondary current |
| C. | primary current is decreased by an increase in secondary current |
| D. | secondary current decrease causes a primary current increase |
| Answer» C. primary current is decreased by an increase in secondary current | |
| 104. |
In a transformer, what will happen to the primary current if the secondary magnetic field increases? |
| A. | Ip will increase. |
| B. | Ip will be canceled. |
| C. | Ip will remain the same. |
| D. | Ip will decrease. |
| Answer» B. Ip will be canceled. | |
| 105. |
The time required for one weber of flux to cut a conductor and produce one volt is: |
| A. | one revolution |
| B. | one second |
| C. | one millisecond |
| D. | four revolutions |
| Answer» C. one millisecond | |
| 106. |
What is the phase angle of a 24 Vac parallel RL circuit when R = 45 ohms and XL = 1100 ohms? |
| A. | 0.001 degrees |
| B. | 2.300 degrees |
| C. | 87.600 degrees |
| D. | 89.900 degrees |
| Answer» C. 87.600 degrees | |
| 107. |
When an electromagnet reaches maximum strength, it is considered to be: |
| A. | in field condition |
| B. | at saturation |
| C. | inhibited |
| D. | at field strength |
| Answer» C. inhibited | |
| 108. |
Faraday's law states that the: |
| A. | direction of the induced voltage produces an opposition |
| B. | direction of an induced current produces an aiding effect |
| C. | emf depends on the rate of cutting flux |
| D. | emf is related to the direction of the current |
| Answer» D. emf is related to the direction of the current | |
| 109. |
Which of the following represents a true equivalent of an inductor? |
| A. | An inductance in series with a resistance and a capacitance |
| B. | A capacitance in parallel with the series combination of a resistance and an inductance |
| C. | An inductance in parallel with the series combination of a resistance and a capacitance |
| D. | The only quality a real inductor has is inductance. |
| Answer» C. An inductance in parallel with the series combination of a resistance and a capacitance | |
| 110. |
If the switch is moved to position 1 in the given circuit, how long will it take for the current to reach its maximum value? |
| A. | 72.5 s |
| B. | 532 s |
| C. | 610 s |
| D. | 833 s |
| Answer» C. 610 s | |
| 111. |
Electromagnetic induction is the generation of: |
| A. | electricity from magnetism |
| B. | electricity from electricity |
| C. | magnetism from electricity |
| D. | magnetism from magnetism |
| Answer» B. electricity from electricity | |
| 112. |
The inductive reactance of L2 is _____ in the given circuit. |
| A. | 3.5 k |
| B. | 4.4 k |
| C. | 16.3 k |
| D. | 23.3 k |
| Answer» C. 16.3 k | |
| 113. |
Which coil would be used as a step-up transformer primary if coil number 1 has 100 more turns than coil number 2? |
| A. | The coil windings must be the same. |
| B. | coil 1 |
| C. | The coil ratio is too small. |
| D. | coil 2 |
| Answer» E. | |
| 114. |
The time difference, or lag, between flux density and magnetizing force is known as: |
| A. | eddy current |
| B. | magnetic saturation |
| C. | hysteresis |
| D. | coercivity |
| Answer» D. coercivity | |
| 115. |
Which of the following is NOT one of the three major types of fixed inductor? |
| A. | air core |
| B. | ferrite core |
| C. | magnesium core |
| D. | iron core |
| Answer» D. iron core | |
| 116. |
Maximum power will transfer across a transformer when the primary impedance equals the secondary impedance. |
| A. | 1 |
| B. | |
| C. | 1 |
| D. | |
| Answer» B. | |
| 117. |
When current in an inductor starts to change, it cannot react instantly due to: |
| A. | fixed coil resistance |
| B. | eddy current generation |
| C. | applied emf of the circuit |
| D. | the counter emf of the coil |
| Answer» E. | |
| 118. |
If the primary of a 4:1 turns transformer dissipates 5 W, what is the secondary power? |
| A. | 5.0 W |
| B. | 1.25 pW |
| C. | 9.5 W |
| D. | 20.0 mW |
| Answer» B. 1.25 pW | |
| 119. |
What is the total inductance, assuming no mutual inductance? |
| A. | 12 mH |
| B. | 6 mH |
| C. | 0.73 mH |
| D. | 0 mH |
| Answer» B. 6 mH | |
| 120. |
A turns ratio of 5 for a transformer implies: |
| A. | more primary turns than secondary turns |
| B. | more secondary current than primary current |
| C. | larger source impedance than load impedance |
| D. | more secondary turns than primary turns |
| Answer» E. | |
| 121. |
The ___ cannot change instantaneously in an inductor. |
| A. | voltage |
| B. | current |
| C. | power |
| D. | magnetic field |
| Answer» C. power | |
| 122. |
A magnetic circuit breaker will open to protect equipment only when: |
| A. | voltage is exceeded |
| B. | an open is in the equipment |
| C. | the equipment is operating properly |
| D. | current is exceeded |
| Answer» E. | |
| 123. |
What is the approximate time for a complete decay of 400 mA of inductor current, when R = 10 ohms and L = 20 H? |
| A. | 10 seconds |
| B. | 8 seconds |
| C. | 4 seconds |
| D. | 2 seconds |
| Answer» B. 8 seconds | |
| 124. |
What is the permeability of transformer iron? |
| A. | 50 |
| B. | 450 |
| C. | 1500 |
| D. | 5500 |
| Answer» E. | |
| 125. |
Fixed transformers have: |
| A. | a center-tapped secondary |
| B. | multiple windings |
| C. | turns ratios that cannot be changed |
| D. | a multiple-tapped secondary |
| Answer» D. a multiple-tapped secondary | |
| 126. |
Find VR and VL. |
| A. | VR = 41.6 V, VL = 78.4 V |
| B. | VR = 48 V, VL = 110 V |
| C. | VR = 56 V, VL = 106 V |
| D. | VR = 60 V, VL = 60 V |
| Answer» D. VR = 60 V, VL = 60 V | |
| 127. |
A voltage is induced in a transformer secondary winding by the action of the: |
| A. | secondary magnetic field |
| B. | primary turns ratio |
| C. | primary magnetic field |
| D. | secondary counter emf |
| Answer» D. secondary counter emf | |
| 128. |
As a generator armature passes the 270 degree point, the induced voltage is: |
| A. | at maximum negative |
| B. | between maximum negative and zero |
| C. | at maximum positive |
| D. | between zero and maximum positive |
| Answer» B. between maximum negative and zero | |
| 129. |
What is the phase angle between the source voltage and current, when a 100 mH inductor with a reactance of 6 k, and a 1 k resistor are in series with a source? |
| A. | 0.1 degrees |
| B. | 9.0 degrees |
| C. | 61.0 degrees |
| D. | 81.0 degrees |
| Answer» E. | |
| 130. |
In a purely inductive circuit, |
| A. | current leads voltage by 90° |
| B. | voltage lags current by 90° |
| C. | voltage leads current by 90° |
| D. | voltage and current are in phase (0°) |
| Answer» D. voltage and current are in phase (0¬∞) | |
| 131. |
In the given circuit, what will the voltage be across R3 25 s after the switch is moved to position 2? |
| A. | 2.88 V |
| B. | 5.9 V |
| C. | 8.34 V |
| D. | 14 V |
| Answer» C. 8.34 V | |
| 132. |
How long until the current is at a maximum? |
| A. | 0 s |
| B. | 5 s |
| C. | 15 s |
| D. | 25 s |
| Answer» C. 15 s | |
| 133. |
What is magnetic flux? |
| A. | the number of lines of force in webers |
| B. | the number of lines of force in maxwells |
| C. | the number of lines of force in teslas |
| D. | the number of lines of force in flux density |
| Answer» B. the number of lines of force in maxwells | |
| 134. |
What happens when moving expanding lines of force encounter a conductor? |
| A. | Current increases. |
| B. | Voltage is induced. |
| C. | Resistance is reduced. |
| D. | Power is increased. |
| Answer» C. Resistance is reduced. | |
| 135. |
During a current change, the ability of a conductor to produce counter emf within itself is called: |
| A. | back emf |
| B. | self-induction |
| C. | a henry |
| D. | impedance |
| Answer» C. a henry | |
| 136. |
What is the current rise after 2 time constants if Vs = 12 V dc, R = 60 , and the inductor is rated at 24 mH? |
| A. | 79.9 mA |
| B. | 126.4 mA |
| C. | 173.0 mA |
| D. | 198.6 mA |
| Answer» D. 198.6 mA | |
| 137. |
After a voltage has been applied to an inductor, the current will be ___ of its full value after 2 time constants. |
| A. | 0.63 |
| B. | 0.86 |
| C. | 0.95 |
| D. | 0.98 |
| Answer» C. 0.95 | |
| 138. |
The unit of flux density is: |
| A. | magnetomotive force |
| B. | a weber |
| C. | a maxwell |
| D. | a tesla |
| Answer» E. | |
| 139. |
What is the inductive reactance if the Q of a coil is 60, and the winding resistance is 5 ? |
| A. | 0.083 |
| B. | 12 |
| C. | 30 |
| D. | 300 |
| Answer» E. | |
| 140. |
If you wanted to decrease the inductance of a coil, you might increase the: |
| A. | number of turns |
| B. | permeability of the core |
| C. | spacing between turns |
| D. | area of the coil |
| Answer» D. area of the coil | |
| 141. |
The electrical energy consumed by a coil is stored in the form of: |
| A. | an electrical field |
| B. | a force field |
| C. | an electrostatic field |
| D. | a magnetic field |
| Answer» E. | |
| 142. |
What type of device consists of a coil with a moveable iron core? |
| A. | solenoid |
| B. | reed switch |
| C. | relay |
| D. | armature |
| Answer» B. reed switch | |
| 143. |
You could decrease the time constant of an RL circuit by |
| A. | adding a resistor in parallel with the circuit resistance |
| B. | adding an inductor in series with the circuit inductance |
| C. | decreasing the amplitude of the input voltage |
| D. | exchanging the position of the resistor and inductor in the circuit |
| Answer» C. decreasing the amplitude of the input voltage | |
| 144. |
What is hysteresis? |
| A. | lead between cause and effect |
| B. | lag between cause and effect |
| C. | lead between voltage and current |
| D. | lag between voltage and current |
| Answer» C. lead between voltage and current | |
| 145. |
When a load is not connected to the secondary of a transformer: |
| A. | primary current is zero |
| B. | primary current is inversely proportional to primary impedance |
| C. | secondary voltage is zero |
| D. | secondary voltage is proportional to primary impedance |
| Answer» C. secondary voltage is zero | |
| 146. |
The polarity of induced voltage while a field is collapsing is: |
| A. | independent of the force creating it |
| B. | opposite to the force creating it |
| C. | identical to the force creating the field |
| D. | present only if the force is stationary |
| Answer» C. identical to the force creating the field | |
| 147. |
The primary winding of a transformer is the side connected to the load. |
| A. | 1 |
| B. | |
| C. | 1 |
| D. | |
| Answer» C. 1 | |
| 148. |
A practical inductor |
| A. | has inductance |
| B. | has winding resistance |
| C. | has winding capacitance |
| D. | all of the above |
| Answer» E. | |
| 149. |
What is the total inductance assuming no mutual inductance? |
| A. | 0 mH |
| B. | 0.69 mH |
| C. | 12 mH |
| D. | 24 mH |
| Answer» C. 12 mH | |
| 150. |
As current travels within a conductor: |
| A. | the magnetic field aids the current |
| B. | a magnetic field is developed around it |
| C. | the wire tries to point north |
| D. | an electrostatic field opposes the current |
| Answer» C. the wire tries to point north | |