June 25, 2014

What is wattless current? | Target GATE 2015 | ECE | EEE | EIE

22:21 Posted by Durga swaroop Perla , No comments
Watt-less Current?
Watt is the unit of power. So, whenever power is absorbed by an element it is measured in Watts.
So, for example, when a current flows through a Resistor, the Power is dissipated as heat. So, when current flows through a resistive element some power is dissipated, measured in Watts.
 
So, Now, as you might expect, Watt-less current is the current which doesn't dissipate any power. How, is that possible you ask, lets see how.
The Power in an AC Circuit is given by the following relation. P = V.I.Cos(Ø)
Ø, being the phase angle between Applied voltage and the Alternating Current.
The Quantity Cos(Ø) is also called as Power Factor.
The Phase angle, Ø, is zero for Resistors.

June 18, 2014

Solution | Question of the Day 1 | GATE - 2015 | ECE | EEE

00:29 Posted by Durga swaroop Perla No comments
Actual Question - Click here
In the given circuit the input is an Voltage source which has a value of 10.u(t), where u(t) is the Unity Step Function.  The Resistance of the Resistor is 1 Ohm. And, two capacitors of 3F and 2F and connected in series to this Resistor as shown in the figure. Find the voltage across the 2F capacitor as a function of time, V(t).
Assume the Capacitors are initially carrying zero charge.
 
 

Answer : V(t)=6 - 6.e^(-5/6 t)
So, That was the question and the answer. Before you proceed to solving the question, there are a few things you need to take a look at.
  1. Laplace Transforms & Inverse Laplace Transforms
  2. Basic Circuit relations (KVL, KCL, Voltage Division, Current Division)
  3. Basics of RL, RC, RLC circuits

June 17, 2014

Question of the Day 1 | GATE - 2015 | ECE | EEE

00:08 Posted by Durga swaroop Perla 3 comments

In the given circuit the input is an Voltage source which has a value of 10.u(t), where u(t) is the Unity Step Function.  The Resistance of the Resistor is 1 Ohm. And, two capacitors of 3F and 2F and connected in series to this Resistor as shown in the figure. Find the voltage across the 2F capacitor as a function of time, V(t).
Assume the Capacitors are initially carrying zero charge.
 
 
 
Answer will be given along with the complete solution tomorrow. So, try to solve it and check your solution with the one we will publish tomorrow.
So, Good Luck with your preparation for GATE.
As always, Have a nice day!
 
For Answer and Solution Click here