IIT JEE , AIEEE Forum - Physics , Electricity

newkid

1)In which position of second charge Q, flux of electric field through the hemisphere remains unchanged.

a) A b)B c)C d)D

harsha_27

one of the best questions on Gauss's Law given in H.C.Verma..
the answer is A and D ........i'll post the explanation if u want.............

mohit_jitani

see friend......ne field line passing through B n the hemisphere may or maynot cross the hemisphere again,...so flux may b changed...same is the story wid C ...bt look at A and D ...ne field line passing through them will definitely cut the hemisphere twice...thus producing no change in the net flux....r u satisfied ...if yes then pleez rate me n if nt ..tell me i ll make it clearer..... god bless u

newkid

i think i got it....

but harsha_27 , can you post the solution please

harsha_27

see the electric flux through the hemisphere remains

same only if no charges are induced on the inner

surface of the hemisphere(by Gauss's Law)

and also we know that presence of hemisphere should

not indeed cannot alter the effect of electric field

produced by the charge Q ,means (observe

carefully) the direction and magnitude of electric

field produced by the charge Q in region 1 must not

alter due to the presence of hemisphere in b/w

........so in order that not to happen induced

charges are arranged on the h.s. in such a way that

they exactly continue the lines of force originally

produced by the charge Q .....got it? and rest the

diagram itself explains (see the figures

carefully).............only in figure 1 ,the

arrangement of induced charges effect the flux

through the h.s. .........in fig 2 they won't

......hence A and D are correct ..........got it

now???? want more .............i'm ready to explain

.......so don't hesitate .......hope that doesn't

require .......u've got it by now.........

<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>.>>>

mohit_jitani

i m very sorry to say bt harsha u r nt wholly correct......that is what i think

harsha_27

ok........ tell me what u think mohit

newkid

what if i make the charge distribution like this??

harsha_27

i'm not saying that the distribution must be exactly

as what i've drawn ......it may be sth like that but

the main idea is "presence of hemisphere should

not indeed cannot alter the effect of electric field

produced by the charge Q ,unless it is a

non-conducting one " the distribution may be sth like

below see i've drawn the net field lines also.......

newkid

u r confusing me friend

make it clear...

can i expect some experts view???

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