Some HC Verma Doubts

question 1 : a small analogy :

Population of a country is 12345 and the area is 10 sq metre.......so population density is 1234.5 ........(which isn't an integer.LOL !!! )

can anyone answer Q 4 & 6

thanks

@ sunny ... (:

@ sengupta..if the concept of physical electric field lines is not applicable then plz also share with us that WHY do electromagnetic signals take a time of D/c to reach a place at a distance 'D' away from the source.In physics we come across many entities of the nature that are not seen yet their effects can be measured..WITH PPL LIKE U AROUND IT MUST HAVE BEEN DIFFICULT FOR THE INVENTORs TO develop devices working on emwaves/infrared/radio/xray.....just bcoz you do not see anything does not imply that it does not exist......and ..by the way.. have YOU seen even an electron..upto now??or you have been MUGGING UP the facts about electrostats..electric current..gauss
:p
DO NOT VISIT SITES LIKE viziq instead try to know about facts from real people @ALBERT EINSTEIN..STEPHEN HAWKING..ROGER PENROSE..STUART HAMEROFF..JOHN LUCAS..ERNST MACH..WOLFGANG PAULI..

3.sandeep i think we get to see only 1 hemisphere of the moon,the other can be seen only by pictures taken from shuttles or satellites that can view the other half.

This is in reply to Prateek's post on 31st July. If lines of force existed in reality then we should have seen such lines coming out of a magnet. You must have seen a bar magnet. Have you seen such lines coming out? On the contrary if you remember how those lines were plotted during the practical class then you will remember that they were traced by placing the needle at various points which were later joined. That is precisely what is the meaning of line of force. It gives you the direction of the needle at that point. My advice will be if you have such flawed concepts then you should try and answer many questions which you can easily find at http://www.wiziq.com/tests/teacher/11908-APT-ACADEMIC-SOLUTIONS

6.
if the object is virtual

sandeep reply to karo apne post par ..

sandeep boss where r u ??

WHEN TALL BUILDINGS R CONSTRUCTD THE DURATION OF DAY AND NIGHT INCRSES :: only for the workers and the managemnet involved in the construction... :D lolz..!! :)

Everything in the universe will also include you+metre scale :D
OTHRWISE THIS CAN'T B POSSIBLE :D
..so naturally if you consider yourself standing with a metre scale kept ppndicular to a wall ahead..while the size of wall ,ground ,urself and the metrescale doubles ..NO-ONE CAN SAY WHETHER THERE WAS AN ABSOLUTE INCREASE IN THE SIZE OR NOT....

we [[as humans]] are 'only' capable of measuring the dimensions relative::
1)length 2)mass 3)luminous intensity 4)temperature 5) time 6) space
7)amount of substance
as you never know what is the absolute of any of these ..derived quantities like: MOTION , FORCE ,DENSITY etc are naturally relative too..!!

59% of the moon is visible to us.This arises due to a spl. case (ORBITAL PERIOD OF MOON = ROTATIONAL PERIOD)..as a result of which 50% moonis visible to us ..however[+9% bcoz] the orbit of the moon is elliptical so at the farthest side (of the orbit) the moon slows down

@ sengupta ..lines of force do exist in real ..that is why ..there's a concept of time delay arising
(FOR EXPERIENCING THE ELEC. FIELD) when any electronic charge is suddenly brought into existence.