Question
Two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from thecodes(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 resistivity of a semiconductor increases with temperature.
Reason: The atoms of a semiconductor vibrate with larger amplitude at higher temperatures thereby increasing its resistivity.

Answer

  1. A is false and R is also false.

Explanation:

With the increase of temperature, the average energy exchanged in a collision increases and so more valence electrons can cross the energy gap, thereby increasing the electron-hole pairs. As in a semiconductor, conduction occurs mainly through electron-hole pairs, so conductivity increases with increase of temperature. Which in turn implies that the resistivity of a semiconductor decreases with rise in temperature.

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For question, 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.
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  4. A is false and R is also false.
Assertion (A): There is a chain reaction when uranium is bombarded with slow neutrons.

Reason (R): When uranium is bombarded with slow neutrons, more neutrons are produced.

For question, 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.
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  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 (A): Isotopes of an element can be separated by using a mass spectrometer.
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  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and Rare 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 (A): An aircraft flies along the meridian, the potential develops at the ends of its wings.
Reason (R): Whenever there is change in the magnetic flux e.m.f. induces.
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: Soft iron is used as a core of transformer.
Reason: Area of hysteresis loop for soft iron is small.
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: In an electromagnetic wave, magnitude of magnetic field vector is much smaller than the magnitude of electric field vector.
Reason: Energy of electromagnetic waves is shared equally by the electric and magnetic fields.
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.
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  3. A is true but R is false.
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Assertion (A): At neutral point, a compass needle point out in any arbitrary direction.
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  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true but R is false.
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Assertion (A): Sharper is the curvature of spot on a charged body lesser will be the surface charge density at that point.
Reason (R): Electric field is non-zero inside a charged conductor.
Assertion (A): Two adjacent conductors of unequal dimensions, carrying the same positive charge have a potential difference between them.
Reason (R): The potential of a conductor depends upon the charge given to it.
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  2. Both A and R are true but R is NOT the correct explanation of A.
  3. A is true but R is false.
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Assertion (A): Magnetic moment is measured in joule/ tesla or amp m2.
Reason (R): Joule/ tesla is equivalent to amp m2.
Assertion (A): The photoelectrons produced by a monochromatic light beam incident on a metal surface have a spread in their kinetic energies.
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