Download App

Magnetism And Matter — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsMagnetism And Matter1 Mark
Question
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 (A): A compass needle when placed on the magnetic north pole of the earth rotates in vertical direction.
Reason (R): The earth has only horizontal component of its magnetic field at the north poles.
✓

Answer

  1. A is false and R is also false.
Explanation:
The earth has only vertical component of its magnetic field at the magnetic poles. Since compass needle is only free to rotate in horizontal plane. At north pole the vertical component of earth's field will exert torque on the magnetic needle so as to align it along its direction. As the compass needle can not rotate in vertical plane, it will rest horizontally, when placed on the magnetic north pole of the earth.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "Assertion (A) & Reason (B) MCQ" from Magnetism And Matter→Magnetism And Matter — all question types→Physics STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

For question 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. Assertion $(A)$: Two point coherent sources of light $S_1$ and $S_2$ are placed on a line as shown. $ P$ and $Q$ are two points on that line. If at point $P$ maximum intensity is observed then maximum intensity should also be observed at $Q$.

Reason $(R)$: In the figure of assertion the distance $|S_1P - S_2P|$ is equal to distance $|S_2Q- S_1Q|.$
→
For question two statements are given$-$one labelled Assertion $(A)$ and the other labelled Reason $(R).$ Select the correct answer to these questions front the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion $(A):$ Mass of moving photon varies inversely to the wavelength.
Reason $(R):$ Energy of the particle $=$ Mass $\times ($Speed of light$)^2$​​​​​​​
→
For question two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions front 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 (A): A photon has no rest mass, yet it carries definite momentum.
Reason (R): Momentum of photon is due to its energy and hence its equivalent mass.
→
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 (A): When a dielectric medium is filled between the plates of a condenser, its capacitance increases.
Reason (R): The dielectric medium reduces the potential difference between the plates of the condenser.
→
For question two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions front 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 (A): The threshold frequency of photoelectric effect supports the particle nature of light.
Reason (R): If frequency of incident light is less than the threshold frequency, electrons are not emitted from metal surface.
→
Assertion (A): If a proton and electron are moving with same velocity, then wavelength of de-Broglie wave associated with electron is longer than that associated with proton.
Reason (R): The wavelength of de-Broglie wave associated with a moving particle is inversely proportional to its mass.
→
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.
Assertion $(A):$ As force is a vector quantity, hence electric field intensity is also a vector quantity.
Reason $(R):$ 'Tile unit of electric field intensity is newton per coulomb.
→
For question 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 (A): Interference obeys the law of conservation of energy.
Reason (R): The energy is redistributed in case of interference.
→
For question 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 (A): In He-Ne laser, population inversion takes place between energy levels of neon atoms.
Reason (R): Helium atoms have a meta-stable energy level.
→
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 dominant mechanism for motion of charge carriers in forward and reverse biase silicon p-n junction are drift in both forward and reverse bias.
Reason: In reverse biased, no current flow through the junction.
→