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Multiple choice physics magnetic effects of electric current direct current types of current movement of charge

The function ${\sin}^{2}{\omega t}$ represents:

  1. a periodic, but not simple harmonic, motion with a period $2\pi/\omega$

  2. a periodic, but not simple harmonic, motion with a period $\pi/\omega$

  3. a simple harmonic motion with a period $2\pi /\omega$

  4. a simple harmonic motion with a period $\pi /\omega$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Using the identity sin^2(wt) = (1 - cos(2wt)) / 2, the motion is simple harmonic with an angular frequency of 2w, meaning the period is 2pi / (2w) = pi / w.

Multiple choice physics magnetic effects of electric current direct current types of current movement of charge

What will be the reading of a hot wire voltmeter if it is connected across the terminals of a generator whose voltage wave form is represented by 
$V = 200\sin \omega t + 100\sin 3\omega t + 50\sin 5\omega t$?

  1. 100V

  2. 162 V

  3. 150 V

  4. 200 V
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The RMS value of a complex waveform is the square root of the sum of the squares of the RMS values of its individual harmonic components. RMS = sqrt((200/sqrt(2))^2 + (100/sqrt(2))^2 + (50/sqrt(2))^2) = sqrt(20000 + 5000 + 1250) = sqrt(26250) approx 162V.

Multiple choice physics magnetic effects of electric current direct current types of current movement of charge

Which of the following is wrong?

  1. It is not possible to have electrolysis by a.c.

  2. Ordinary batteries cannot be changed by a.c.

  3. In a circuit containing L, C and R in series across a steady source, poer is dissipated in R, at steady state

  4. For current dirven from a steady source by an ohmic conductor, mean value and r.m.s. value of current will be same
Reveal answer Fill a bubble to check yourself
A Correct answer