Question

For making a standard resistance, wire of the following material is used.
1) Nichrome
2) Copper
3) Silver
4) Manganin

Answer 1

Hint: We choose alloys for making a standard resistance because alloys are least affected by heat and give high resistance. We need a resistance in a circuit to be stable and provide high resistivity. A resistance that does not change its value gives constant output and that’s what is required.

Complete step by step answer:
Resistance is the property of a material to resist the flow of charges in itself. Resistance is defined as voltage upon current .The best resistance is those resistance (if taking a non-variable circuit) which are stable and don’t change their value. For this to happen we need to make a resistance from a material that doesn’t get affected by temperature, have a less temperature of coefficient and possess high resistivity. The best option would be Manganin; this is so because Manganin as a material has all the above mentioned properties. The above mentioned properties are required because the more stable the resistance would be in a circuit the more stable would be the circuit. The more stable the circuit would be the better and longer it would work and that’s what is required. Manganin and Nichrome is an alloy (made up of a combination of metals) while copper and silver are pure metals. Here Manganin is more stable and heat resistant than Nichrome. Other material also shows some of the properties that are required for making a standard resistance but they didn’t have all the properties.
Final Answer: The correct option (4) Manganin.

Note: Here we have to give proper reasoning of the material (alloys) used in making the standard resistance. Then give a proper reason for choosing Manganin as a material to make a standard resistance. Also note if this would be a multiple choice(more than one correct answer) then Nichrome would also be the correct answer.