Home » 2013 » August (Page 2)

Monthly Archives: August 2013

Questions from Alternating current

1.      Derive an expression for the average power in an ac circuit.
2.      Distinguish between resistance, reactance and impedance.
3.      Draw the phasor diagram showing voltage and current in LCR series circuit and derive an expression for the impedance

Copy of DSC00355
4.      Deduce the phase relationship between current and voltage in an ac circuit containing inductor only
5.      A series LCR circuit with L = 0.12 H, C = 4.8 x 10 7 f and R = 23 ohms is connected to a variable frequency supply.  At What frequency is the current maximum?
9.      A sinusoidal voltage V=200 sin 314t is applied to a resistor of 10 ohms resistance. Calculate (i) rms value of the voltage, (ii) rms value of the current and (iii) power dissipated as heat in watts.

 

(Posted by Sayantika Nath)

Space and Objects

It seems to me that all of physicality is energy and that energy is producing objects as molecular structures.  So, we can further state that all of physicality consists of molecular structure.  These structures “appear” to have boundaries.  When an object moves, how is that affecting the molecular structure of the space in which it is moving?  Is the boundary of space “fluid” to accommodate the moving object as dropping a cube of ice into a glass of water?  Does not the very same space exist regardless the position of the object?

Posted by Larry

Black Hole and Photons

Black hole has such a strong gravitational pull that even photons can’t escape it. How is it possible if they have no mass? How can a black hole exert a gravitational force on photons if they have no mass?

Asked Krunoslav Zazar

larger animation

Learn Physics through Videos

UNITS AND MEASUREMENT

KINEMATICS

ELECTROSTATICS

CURRENT ELECTRICITY

MAGNETIC EFFECTS OF CURRENT

ELECTROMAGNETIC INDUCTION AND AC

ELECTROMAGNETIC WAVES

RAY OPTICS

WAVE OPTICS

Learn Ray Optics through Videos

These videos are very good to revise Ray optics. Try viewing them in full screen

Quantum Locking

I recently watched a program on quantum locking using a super conductor cooled by nitrogen. This brought to mind grapheme as a material which has superconductive properties.The next question I had was obviously this.Can grapheme be used at room temperature to create the state needed for quantum locking?

Mark asked

Drift velocity and current density

Current density is proportional to drift velocity, while drift velocity increases due to acceleration (a=eE/m)current remains same, how?

 

Asked Sabha

%d bloggers like this: