As shown in figure "A" of the illustration,...

🔍 Key Concepts

• Recognize that series contacts in a ladder diagram represent a logical AND condition, while parallel branches represent a logical OR condition. • Understand that the coils labeled IR1 and IR2 are internal relays energized by combinations of inputs, and the final Output coil depends on the states of IR1 and IR2. • Carefully trace which inputs feed IR1 and IR2, and then how IR1 and IR2 are arranged relative to the Output coil (series vs. parallel).

💭 Think About

• For IR1, look at how Input 1 and Input 2 are drawn: are they in series on one path, or are they on separate parallel branches? What logical operation (AND/OR) does that imply? • For IR2, do the same check with Input 3 and Input 4. Then, look at the rung with the Output coil: are IR1 and IR2 in series or parallel? • Once you know whether each pair is AND or OR, and whether IR1 and IR2 themselves are AND or OR, which answer choice’s wording exactly matches that combination?

✅ Before You Answer

• Be sure you can state clearly: "IR1 is energized when ___ and ___" and "IR2 is energized when ___ and ___" before looking at the answer choices. • Verify whether the rung feeding the Output has one path (series) or two branches (parallel) from the left rail to the Output coil; this is critical to choosing between the options that use AND vs. OR between the two relay conditions. • Double-check that you are matching the words "either" and "both" in the choices to the correct visual patterns of OR (parallel) and AND (series) in the diagram.

As shown in figure "A" of the illustration, what input conditions are required to produce an output? Illustration EL-0241

Either "Input 1" or "Input 2" must be closed AND either "Input 3" or "Input 4" must be closed.

Either "Input 1" or "Input 2" must be closed OR both "Input 3" and "Input 4" must be closed.

Both "Input 1" and "Input 2" must be closed AND either "Input 3" or "Input 4" must be closed.

Both "Input 1" and "Input 2" must be closed OR both "Input 3" and "Input 4" must be closed.

🔍 Key Concepts

💭 Think About

✅ Before You Answer