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Current Electricity — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsCurrent Electricity1 Mark
Question
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, and R is also false.
Assertion: The drift velocity of electrons in a metallic wire will decrease, if the temperature of the wire is increased.
Reason: On increasing temperature, conductance of metallic wire decreases.
✓

Answer

  1. Both A and R are true, but R is not the correct explanation of A.
Explanation:

On increasing temperature of wire, the kinetic energy of free electrons increase and so they collide more rapidly with each other, and hence their drift velocity decreases. Also when temperature increases, resistance increase, and resistance is inversely proportional to conductivity of material.

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