MCQ
Alternating current is one which changes in its:
  • A
    direction
  • B
    magnitude
  • C
    magnitude and direction both
  • D
    none

Answer

  1. magnitude and direction both

Explanation:

An alternating current (AC) is an electric current whose magnitude and direction vary, unlike direct current, whose direction remains constant.

The usual waveform of an AC power circuit is a sine wave, because this leads to the most efficient transmission of energy. The sine wave oscillates periodically between positive and negative direction.

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

Similar questions

A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. is.

In a  PN-junction diode

(a) The current in the reverse biased condition is generally very small

(b) The current in the reverse biased condition is small but the forward biased current is independent of the bias voltage

(c) The reverse biased current is strongly dependent on the applied bias voltage

(d) The forward biased current is very small in comparison to reverse biased current

Which of the following is quantised according to Bohr’s theory of hydrogen atom

(a) Linear momentum of electron

(b) Angular momentum of electron

(c) Linear velocity of electron

(d) Angular velocity of electron

Four modifications are suggested in the lens formula to include the effect of the thickness t of the lens. Which one is likely to be correct?

  1. $\frac{1}{\text{v}}-\frac{1}{\text{u}}=\frac{1}{\text{uf}}$

  2. $\frac{1}{\text{v}^2}-\frac{1}{\text{u}}=\frac{1}{\text{f}}$

  3. $\frac{1}{\text{v}-\text{t}}-\frac{1}{\text{u}+\text{t}}=\frac{1}{\text{f}}$

  4. $\frac{1}{\text{v}}-\frac{1}{\text{u}}+\frac{\text{t}}{\text{uv}}=\frac{\text{t}}{\text{f}}$

Assertion  : Isobars are the element having same mass number but different atomic number.

Reason      : Neutrons and protons are present inside nucleus.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

An electron and a proton with equal momentum enter perpendicularly into a uniform magnetic field, then

(a) The path of proton shall be more curved than that of electron

(b) The path of proton shall be less curved than that of electron

(c) Both are equally curved

(d) Path of both will be straight line

If identical charges (-q) are placed at each corner of a cube of side b, then electric potential energy of charge (+q)  which is placed at centre of the cube will be

(a)  

(b)

(c)

(d)

Two radioactive materials  and  have decay constants 10λ  and λ respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of   to that of   will be 1/e  after a time

(a) 1/(10 λ)

(b) 1/(11 λ)

(c) 11(10 λ)

(d) 1(9 λ)

Assertion  :   Magnetism is relativistic.

Reason      : When we move along with the charge so that there is no motion relative to us, we find no magnetic field associated with the charge.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

A capacitor works in: