Biology; Chemistry; Physics: Post your doubts here!

[***amd***]

In a metal wire , when electric current is passed through it , electrons are replaced by NEW electrons?
where do the NEW electrons come from? :/

lol, by new electrons it means as the electrons are flowing.
electron x moves forward and the electron y (which is it its back) takes its position and this way they keep on flowing.

 

[***amd***]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s13_qp_22.pdf
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s13_ms_22.pdf
Q2 (a)
see ms, it states all about its formula. then where did that definition go "turning efffect of force is moment of force"? 0.0

the same ppr, Q6 (b) (i)
funky brat, i remember u said when it is said about current, we consider it "convectional current", so why is it stated in ms that current is "flow of charge/electrons"?

Q8 EITHER (b) (i)

 

[Suhaib]

Thanks man!

 

[kirann]

how to determine resultant force in these type of q's

 

[***amd***]

how to determine resultant force in these type of q's

which book do u have?

 

[***amd***]

how to determine resultant force in these type of q's

for that Q4, u'll apply head-to-tail rule, or paralellogram method. so simply, as both forces on object are equal, the resultant will be their angle bisector.

Q5, it says *turning* in a *horizontal* circle. so the only force in a horizontal direction is D.

 

[kirann]

which book do u have?

physics matters

 

[kirann]

for that Q4, u'll apply head-to-tail rule, or paralellogram method. so simply, as both forces on object are equal, the resultant will be their angle bisector.

Q5, it says *turning* in a *horizontal* circle. so the only force in a horizontal direction is D.

ohh thanks

 

[kirann]

??

 

[kirann]

i did it this way,
p=E/t (E=mgh)
p=mgh/t
my answer was 1200W
which is greater than input
so its not possible, can somebody find the error and tell me the right one
ans is C

 

[kirann]

ok, in this question the radioactive source is place 10cm away from the G.M tube, so alpha partiles will itself stop after 5-6 cm.
beta and gamma is left, beta is deflected by magnetic field but gamma is not, so after defection the GM tube will show count rate of beta or not?
is count rate 1950 for beta and gamma or just for gamma?
the answer is C.

 

[kirann]

i never studied this experiment i think so help!!

 

[Dream.Eater]

ok, in this question the radioactive source is place 10cm away from the G.M tube, so alpha partiles will itself stop after 5-6 cm.
beta and gamma is left, beta is deflected by magnetic field but gamma is not, so after defection the GM tube will show count rate of beta or not?
is count rate 1950 for beta and gamma or just for gamma?
the answer is C.View attachment 42776

Its quite simple..
Without the magnetic field both beta and gamma would be detected. When the field is introduced beta gets deflected by a very large angle because of it's charge and very negligible mass. Therefore gamma passes undevited and reaches the detector so yes 1950 is only for gamma beta no longer reaches the detector

 

[kirann]

Its quite simple..
Without the magnetic field both beta and gamma would be detected. When the field is introduced beta gets deflected by a very large angle because of it's charge and very negligible mass. Therefore gamma passes undevited and reaches the detector so yes 1950 is only for gamma beta no longer reaches the detector

this was the only confusion thanks

 

[kirann]

The ans to that is D (i think) becoz most of the alpha particles fired at the

yes, right!! but how?

 

[Dream.Eater]

yes, right!! but how?

Sorry i typed out only half my reply....before posting by accident
When alpha was fired at gold foil most of the particles went undeviated through the foil and only 1 in 10000 were deflected by a large angle. This led to the conclusion that the mass of an atom is concentrated in a tiny volume at it's centre and that is the nucleus.....

 

[kirann]

Sorry i typed out only half my reply....before posting by accident
When alpha was fired at gold foil most of the particles went undeviated through the foil and only 1 in 10000 were deflected by a large angle. This led to the conclusion that the mass of an atom is concentrated in a tiny volume at it's centre and that is the nucleus.....

is this that gold leaf experiment?

 

[Dream.Eater]

is this that gold leaf experiment?

Yes....
Carried out by Geiger and Marsden who were Rutherford's research workers...

 

[princess Anu]

The current changes its direction in Dc motor while rotating? :S
The function of carbon brushes in DC AC is the same? to reduce friction between the commutators?

 

[kirann]

explain anyone