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Biology; Chemistry; Physics: Post your doubts here!

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how does a low density hydrogen cloud in space becomes a star?
please dont repeat the words of marking scheme..i need some detail
 
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in a.c motor carbon brushs r not used...split ring commutator is used....in DC motor carbon brush is used to chnge diretion of current every half turn so tht coil rotates is same direction..!!!

carbon brushes are used both in AC generator and DC motor to keep contact with circuit without restricting movement!
in AC generator, SLIP rings are used
in DC motor, SPLIT ring commutator is used
 
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carbon brushes are used both in AC generator and DC motor to keep contact with circuit without restricting movement!
in AC generator, SLIP rings are used
in DC motor, SPLIT ring commutator is used
oohhh yeah...... i mixed em up....:oops: :censored:
 
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in a.c motor carbon brushs r not used...split ring commutator is used....in DC motor carbon brush is used to chnge diretion of current every half turn so tht coil rotates is same direction..!!!
is the split-ring commutator function as reverse the current, not the carbon brush?
 
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is the split-ring commutator function as reverse the current, not the carbon brush?
this has been cleared man:

carbon brushes are used both in AC generator and DC motor to keep contact with circuit without restricting movement!
in AC generator, SLIP rings are used
in DC motor, SPLIT ring commutator is used
 
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can anyone explain this
http://www.xtremepapers.com/papers/CIE/Cambridge International O Level/Chemistry (5070)/5070_s11_qp_42.pdf
why is Q6 answer not a?
because in P, the concentration is high, but surface area is low(zinc pieces)
an in Q, the concentration is low, and surface area is high(zinc powder)
wouldnt this account for same speed of reaction??

dude it cant be A becuz here HYDROGEN production is being talkd bout...in a) it is shwn tht is Q more hydrgn is producd wich is NOT the case as less concntratd acid is used here compard to P...so hydrogn gas producd in P wld be double of tht producd in Q.......so it wld be (c)
 
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