Download App

Alternating Current — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsAlternating Current1 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 alternating current lags behind the e.m.f. by a phase angle of $\frac{\pi}{2}$ when A.C. flows through an inductor.
Reason: The inductive reactance increases as the frequency of A. C. source decreases.
✓

Answer

  1. A is true but R is false.
Explanation:
When pure inductor is connected to source of an alternating emf, then instantaneous value of alternating emf is given by $\text{E}=\text{E}_0\sin\omega\text{t},$ and corresponding alternating current is given by $\text{I}=\text{I}_0\sin(\omega\text{t}-\frac{\pi}{2}).$ From these two equations, it follows that alternating current lags behind e.m.f. by a phase angle of $\frac{\pi}{2}.$ The inductive reactance, so when frequency increases correspondingly inductive reactance also increases.

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 Alternating Current→Alternating Current — all question types→Physics STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

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 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): Inductance coil are made of copper.
Reason (R): Induced current is more in wire having less resistance.
→
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): Lines of force are perpendicular to conductor surface.
Reason (R): Generally electric field is perpendicular to equipotential surface.
→
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: Though the same current flows through the live wires and the filament of the bulb but heat produced in the filament is much higher than that in live wires.
Reason: The filament of bulbs is made of a material of high resistance and high melting point.
→
Directions: In the following questions, the Assertions (A) and Reason(s) (R) have been put forward. Read both the statements carefully and choose the correct alternative from the following:
Assertion: Basic difference between an electric lines of force and magnetic lines of force is that former is discontinuous and the latter is continuous or endless.
Reason: No electric lines of force exist inside a charged body but magnetic lines do exist inside a magnet.
  1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
  2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
  3. Assertion is correct but Reason is incorrect.
  4. Both Assertion and Reason are incorrect.
→
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): An electron in hydrogen atom passes from n = 4 to n = 1 level. The maximum number of photons that can be emitted is 4.
Reason (R): Maximum number of photons emitted can only be 4
→
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 $(A)$ : Stopping potential depends upon the frequency of incident light but is independent of the intensity of the light.
Reason $(R)$ : The maximum kinetic energy of the photoelectrons is proportional to stopping potential.
→
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): An electron microscope can achieve better resolving power than an optical microscope.
Reason (R): The de-Broglie wavelength of the electrons emitted from an electron gun with velocity 500m/ s is much less than 500nm.
→
Assertion (A): The photoelectrons produced by a monochromatic light beam incident on a metal surface have a spread in their kinetic energies.
Reason (R): The energy of electrons emitted from inside the metal surface, is lost in collision with the other atoms in the metal.
→
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: X-rays in vacuum travel faster than light waves in vacuum
Reason: The energy of X-rays photon is less than that of light photon.
→
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): Total energy of revolving electron in any stationary orbit is negative.
Reason (R): Energy is a scalar quantity. It can have positive or negative value.
→