JEE Main · 2022 · 29 Jul 2022 · Shift 2 · Current Electricity

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Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: Alloys such as constantan and manganin are used in making standard resistance coils.

Reason R: Constantan and manganin have very small value of temperature coefficient of resistance.

In the light of the above statements, choose the correct answer from the options given below.
  1. (A)Both A and R are true and R is the correct explanation of A.✓ Correct
  2. (B)Both A and R are true but R is NOT the correct explanation of A.
  3. (C)A is true but R is false.
  4. (D)A is false but R is true.

Answer: (A)

Solution

Both statements are true. Constantan and manganin are indeed used in making standard resistance coils because they have very small temperature coefficients of resistance (nearly negligible). This property ensures that the resistance remains almost constant over a wide temperature range, which is essential for standard resistors. The reason correctly explains why these alloys are used for this purpose.

JEE Main · 2022 · 29 Jul 2022 · Shift 2 · Single correct option

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