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# Daily Archives: April 11, 2012

## Change in resistance of a wire on stretching

A WIRE OF LENGTH L AND AREA OF CROSS SECTION A HAS A RESISTANCE R. IF THE WIRE IS STRACHED TO TWICE OF ITS LENGTH WHILE A REMAINS SAME , WHAT IS THE NEW RESISTANCE????

We know that R = ρl/A

When the wire is stretched, there is no change in volume. So if length is doubled then volume will be halved so that volume is constant.

Therefore, the new resistance R’ = 4R

That is the resistance becomes four times its original value.

1. A WIRE OF LENGTH L AND AREA OF CROSS SECTION A HAS A RESISTANCE R. IF THE WIRE IS STRACHED TO TWICE OF ITS LENGTH WHILE A REMAINS SAME , WHAT IS THE NEW RESISTANCE???? ## Why do we represent particle by a group of matter waves and not by single de Broglie wave

Why do we represent particle by a group of matter waves and not by single de Broglie wave? Two representations of a hydrogenic de-Broglie wave; the ring represents the electron's phase as a color, the wavy line shows the phase using a polar plot of a sinus curve. (Photo credit: Wikipedia) ## Problem from Kinematics

A particle moving with constant acceleration describes in the last second of its motion 9/25th of the total.if it starts from rest how long is the particle in motion and through what distance does it move if it describes 6 cm in first sec ### Hits so far @ AskPhysics

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