Ignition Systems Questions and Answers

Answer: A

The system must deliver a spark of sufficient energy at a precisely timed instant to each cylinder in turn. Compression ignition belongs to the diesel engine. The spark lasts a millisecond or so rather than being continuous. Checking which component actually carries the load settles most questions of this kind at once. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Framing the question as which quantity the change acts upon makes the answer follow without calculation.

Answer: B

A coil is a transformer with a large turns ratio, and the collapse of the primary field induces tens of thousands of volts in the secondary. The control unit switches the primary, which makes the last option describe the trigger rather than the transformer. Tracing the requirement back to the physical constraint that produces it makes the answer follow. The shared behaviour explains why these belong together and the differences explain why both exist.

Answer: C

Interrupting the primary current collapses the field rapidly and induces a high voltage in the many turns of the secondary. Self induction genuinely produces several hundred volts in the primary itself, which makes the last option a real but secondary effect. The shared behaviour explains why these belong together and the differences explain why both exist. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: D

Ratios of a hundred to one and upward are usual, and the rapid collapse of the field multiplies the effect far beyond the simple ratio. Some coils genuinely approach a thousand to one, which makes the last option a real figure for certain designs. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. Reading the definition literally, rather than recalling a summary, avoids the usual confusion.

Answer: A

Ten to thirty thousand volts is typical, rising with compression pressure and with a worn gap. Compression raises rather than lowers the required voltage, which makes the second option wrong in its reasoning as well as its figure. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Most errors here come from carrying a result across from a neighbouring case where it does not hold.

Answer: B

Gap width and cylinder pressure are the principal factors, and both rise as a plug wears. Rounded electrodes genuinely do raise the required voltage, which makes the last option a real contributing factor rather than a distractor. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Naming what changes and what stays the same is the reliable route through questions of this shape. Most errors here come from carrying a result across from a neighbouring case where it does not hold.

Answer: C

A richer mixture breaks down at a lower voltage than a lean one, which is why lean running makes misfires more likely. That relationship is one reason lean burn engines need particularly capable ignition systems. Naming what changes and what stays the same is the reliable route through questions of this shape. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. The shared properties explain why these belong to one family, and the differences explain why more than one exists.

Answer: D

The rotor sweeps past the cap segments, delivering the high voltage to each lead in the firing order. The contact breaker times the spark rather than distributing it, which makes the last option confuse the two functions. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. Reading the definition literally, rather than recalling a formula, is the reliable route through questions of this shape.

Answer: A

Cam operated points opened the primary circuit once per cylinder per cycle. The condenser suppresses the arc across them rather than doing the switching. Transistors replaced points from the nineteen seventies. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. Checking which component actually carries the load settles most questions of this kind at once. Most errors here come from carrying across a result from a neighbouring case where it does not hold.

Answer: B

Without it the self induced voltage arcs across the points, burning them and slowing the collapse. Suppressing that arc genuinely does speed the collapse and raise the output, which makes the last option a real consequence of the same action. The order in which the effects act is what decides the outcome, so it is worth establishing first. Tracing the requirement back to the physical constraint that produces it makes the answer follow. The quantity that varies and the quantity that does not are worth naming before any substitution is attempted.