Question
The instantaneous voltage through a device of impedence $20\Omega$ is $\text{e}=80\sin100\pi\text{t}.$ The effective value of the current is.

Answer

Given equation, $\text{e}=80\sin100\pi\text{t}.(\text{i})$
Standard equation of instantaneous voltage given by $E = \text{e}_\text{m}\sin(\omega\text{t})......(\text{i})$
Compare $(i)$ and $(ii),$ we get $e_m​ = 80V$
where $e_m$​ is the voltage amplitude.
Current amplitude $\text{I}_\text{m}=\frac{\text{e}_\text{m}}{\text{Z}}$ where $Z =$ impedence
$=\frac{80}{20}=4\text{A}$
$\text{I}_\text{r.m.s}=\frac{4}{\sqrt{2}}=\frac{4\sqrt{2}}{2}=2\sqrt{2}=2.828\text{A}$

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

Similar questions

The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then:
The ionisation energy of $10$ times ionised sodium atom is
The self$-$induced $\text{e.m.f.}$ in a $0.1 H$ coil when the current in it is changing at the rate of $200$ ampere/second  is
If the velocity of a charged particle is made twice and that of magnetic field is made half then the radius of the circular path of the charged particle in the magnetic field will become :
In Rutherford scattering experiment, what will be the correct angle for α scattering for an impact parameter b = 0(a) 90°(b) 270°(c) 0°(d) 180°
       
The work done in bringing a 20 coulomb charge from point A to point B for distance 0.2m is 2J. The potential difference between the two points will be (in volt)(a) 0.2(b) 8(c) 0.1(d) 0.4
       
The chemical equivalent of copper and zinc are 32 and 108 respectively. When copper and silver voltameter are connected in series and electric current is passed through for sometimes, 1.6 g of copper is deposited. Then, the mass of silver deposited will be(a) 3.5 g  (b) 2.8 g(c) 5.4 g  (d) None of these
       
What is the ratio of the speed of infrared and ultraviolet rays in a vacuum?
Photons absorbed in matter are converted to heat. A source emitting n photon/sec of frequency ν is used to convert 1kg of ice at 0°C to water at 0°C. Then, the time T taken for the conversion:
Who is responsible for the photoelectric effect experiment?