In this IIT JEE physics video, we are going to discuss the topic alternating currents. In this physics video we are going to cover the following topics;

- What is alternating current?
- Voltage amplitude
- Angular frequency
- Average value of current or voltage

So let’s begin with what is alternating current. Alternating current is also called as AC. It changes with time. These days a universal standard is built up and according to AC is basically a sinusoidal current or simple harmonically varying currents or voltages. It can be represented as V= V0Sinωt or V= V0cosωt. Similarly, the current can be written as I= I0Sinωt. The potential difference or P.D. between two points is known as voltage. Moving on to voltage amplitude, it is denoted by V. And V= V0Sinωt or V= V0cosωt. V0 is the maximum value of voltage amplitude at some instant. Its graph is also given in the above video. Next, we have the angular frequency. Angular frequency is denoted by ω. We know that ω=2πn, where n is the frequency of A.C. voltage or current. The last topic in the above video is the Average value of current or voltage. V (t) = V0Sinωt. Now we need to find the average value of voltage in one cycle. In this **video lectures** for iit jee physics power factor is most important topic. In IIT JEE exams many questions are asked on power factor. In the last we will learn about alternator and transformer. We learn only ideal transformer in class 12th physics.

The useful energy comes to our home via transformer that we learn in this** video lecture for jee physics**. Before this physics lesson we must study electromagnetic induction unless we cannot understand mutual induction etc. In this chapter we learn about three types of circuit elements. These are resistance, inductance and capacitance. Based on this we make R, L, C, LC, RC, LR and RLC ckts. We study all these circuits are series combination only. Only one parallel combination of LC we also study in this lecture video of physics.