Download App

Alternating Current — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsAlternating Current2 Marks
Question
Distinguish between the terms 'average value' and 'rms value' of an alternating current. The instantaneous current from an a.c. source is I = 5 sin (314 t) ampere.
What are the average and rms values of the current?
✓

Answer

Average value of an alternating current over time T is
$\text{I}_{\text{AV}} = \frac{1}{\text{T}}\int\limits_{0}^{T}\text{I}(\text{t})\text{dt}$
rms value of an alternating current is that value of stready current which when flowing through a resistance for a certain amount of time produces same amount of heat as the given A.C. does in the same resistance in the same time.
Average value over half cycle is ${2\over\pi}\text{I}_{0} = 3.18\text{A}$
or Aveage value over complete cycle is zero
rms value is ${\text{I}_{0}\over\sqrt{2}} = 3.54\text{A}\text{ or }{5\over\sqrt{2}}\text{A}.$

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 "Short Answer Type Questions [2M]" from Alternating Current→Alternating Current — all question types→Physics STD 12 Science question papers→Bihar Board STD 12 Science question papers→Bihar Board question paper generator→

Similar questions

Explain the photoelectric effect when the radiation is incident on different metals?
→
The eyepiece of an astronomical telescope has a focal length of 10cm. The telescope is focused for normal vision of distant objects when the tube length is 1.0m. Find the focal length of the objective and the magnifying power of the telescope.
→
Give a brief explanation about Radioactivity.
→
The yield point of a typical solid is about 1%. Suppose you are lying horizontally and two persons are pulling your hands and two person are pulling your legs along your own length. How much will be the increase in your length if the strain is 1%? Do you think your yield point is 1% or, much less than that?
→
Differentiate between electric lines of force and magnetic lines of force.
→
A parallel plate capacitor of capacitance C is charged to a potential V. It is then connected to another uncharged capacitor having the same capacitance. Find out the ratio of the energy stored in the combined system to that stored initially in the single capacitor.
→
Draw the graph of variation in potential difference and electric field with distance ' $r$ ' for a point electric charge $Q$.
→
Write down the equation of electric potential for a point - outside the spherical shell - on the surface of a spherical shell and - inside the spherical shell.
→
A spectroscopic instrument can resolve two nearby wavelengths $\lambda$ and $\lambda+\Delta\lambda$ if $\frac{\lambda}{\Delta\lambda}$ is smaller than 8000. This is used to study the spectral lines of the Balmer series of hydrogen. Approximately how many lines will be resolved by the instrument?
→
Two capacitors of capacitance $3 \mu F$ and 4 $\mu F$ are charged separately from a 6 V battery. When the battery is removed, they get connected to each other. In which the negative plate of one capacitor is connected to the positive plate of the other. Calculate the total final energy.
→