Match the following materials with their corresponding resistivity values.

Material	Resistivity (Ω m)
(a) Silver	(i) 44×10⁻⁶ Ω m
(b) Manganin	(ii) 1.6×10⁻⁸ Ω m
(c) Diamond	(iii) 10¹² Ω m

1. A

   (a)-(i); (b)-(ii); (c)-(iii)

2. B

   (a)-(iii); (b)-(ii); (c)-(i)

3. C

   (a)-(ii); (b)-(i); (c)-(iii)

4. D

   (a)-(ii); (b)-(iii); (c)-(i)

Appeared in: RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Explanation

• Silver is an excellent electrical conductor and thus has the lowest resistivity (1.6×10⁻⁸ Ω m) among the choices.
• Diamond is a superior electrical insulator, which means it has an extremely high resistance to current flow, corresponding to the highest resistivity value (10¹² Ω m).
• Manganin is an alloy specifically designed for resistors. Its resistivity (44×10⁻⁶ Ω m) is intermediate, being much higher than a conductor but vastly lower than an insulator.
• The correct matching sequence is therefore: Silver (conductor) → lowest resistivity, Diamond (insulator) → highest resistivity, and Manganin (alloy) → intermediate resistivity.

Why Other Options Were Wrong

• Option A: This option incorrectly matches Silver with the resistivity of Manganin (44×10⁻⁶ Ω m) and Manganin with the resistivity of Silver (1.6×10⁻⁸ Ω m). A conductor like Silver must have lower resistivity than an alloy like Manganin.
• Option B: This option incorrectly assigns the highest resistivity (insulator value) to Silver and the intermediate resistivity (alloy value) to Diamond. This is the opposite of their actual properties.
• Option D: This option correctly matches Silver but incorrectly swaps the resistivities of Manganin and Diamond. It assigns the insulator's high resistivity to the Manganin alloy and the alloy's intermediate resistivity to the Diamond insulator.

Related Visual

• Visual 1: Chart - A logarithmic scale showing the resistivity spectrum from conductors (like Silver) through semiconductors and alloys (like Manganin) to insulators (like Diamond). This helps visualize the vast differences in their electrical properties.

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Electrical resistivity of conductors, alloys, and insulators as background academic context rather than a clinical decision trigger.
• Understanding material resistivity is crucial in medical device design. Conductive materials like silver are used in electrodes (e.g., for ECG) and internal wiring of devices to ensure efficient signal transmission.
• Insulating materials are vital for safety, forming the casing of electrical medical equipment and the sheathing of wires to prevent electric shocks to patients and operators.
• Resistive alloys like Manganin are used in precision electronic components within medical instruments where stable resistance is required for accurate measurements.

How to Approach the Question

• First, categorize each material based on its electrical properties: Silver is a conductor, Diamond is an insulator, and Manganin is an alloy.
• Recall or deduce the general order of resistivity for these categories: Insulators have the highest resistivity, conductors have the lowest, and alloys have an intermediate value.
• Arrange the given resistivity values in order from lowest to highest: 1.6×10⁻⁸ Ω m < 44×10⁻⁶ Ω m < 10¹² Ω m.
• Match the material category to the corresponding value: Conductor (Silver) → lowest value, Insulator (Diamond) → highest value, Alloy (Manganin) → intermediate value.
• Based on this matching, identify the correct combination from the given options.

Concept Tested & Keywords

• Concept Tested: Electrical resistivity of conductors, alloys, and insulators.
• Stem keywords: Material, Resistivity, Silver, Manganin, Diamond
• Lead-in keywords: Match the following
• Negative lead-in flag: false

Question ID

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