Ideal machine — efficiency value: By definition, the efficiency of an ideal (lossless) machine is:

Introduction / Context:
Efficiency compares the useful output to the input. In machines, losses due to friction, deformation, and slip reduce efficiency below 100%. Understanding the limiting “ideal” case is vital for benchmarking real designs.

Given Data / Assumptions:

• Efficiency η = Output / Input = M.A. / V.R.
• An ideal machine has no energy losses.

Concept / Approach:
In an ideal machine, all input work converts to useful output work. Therefore Output = Input for any load–movement pair, so η = 1 or 100%. Real systems always have η < 100% due to friction and other dissipative mechanisms; good designs aim to get close but never exceed 100%.

Step-by-Step Solution:
Recall definition: η = M.A. / V.R.Ideal condition: M.A. equals V.R.; thus η = 1.Convert to percent: 1 * 100% = 100%.Hence, the correct answer is 100%.

Verification / Alternative check:
Energy viewpoint: Input work W_in = Effort * effort distance; Output work W_out = Load * load distance. For an ideal machine W_out = W_in, confirming η = 100%.

Why Other Options Are Wrong:

• Ranges below 100% describe realistic but not ideal machines.

Common Pitfalls:

• Confusing “high efficiency” with “ideal”; ideal is a theoretical limit used for comparison, not typically achievable.

Final Answer:
100%