Biology; Chemistry; Physics: Post your doubts here!

[exploded diper]

what is the use of millibar ?

did u read this in any paper?
millibar is a unit for measuring pressure..it is a 100 pascals

 

[DaniyalK]

Need explanation for 32 and 33.

 

[exploded diper]

Need explanation for 32 and 33.

in 33:
the pole produced at the end where the magnet is will always be opposite to the pole on the magnet and hence the coil would produce repulsion force and it will move away frm the magnet

 

[Awesome12]

Need explanation for 32 and 33.

Since 33 has already been explained I will explain 32
A split ring commutator is responsible for moving the coil once it reaches the vertical position. So without it, the coil cannot pass by the vertical position and will stay there

 

[exploded diper]

Since 33 has already been explained I will explain 32
A split ring commutator is responsible for moving the coil once it reaches the vertical position. So without it, the coil cannot pass by the vertical position and will stay there

isnt inertia responsible for the coil to keep on moving....

 

[DaniyalK]

If you think about it, the coil cannot go past the vertical position because both of its ends are fixed to the circuit. The split rings allow it to go past the vertical position, because they can 'disconnect' themselves from the circuit for a brief moment and make the 180 degree turn.

 

[exploded diper]

If you think about it, the coil cannot go past the vertical position because both of its ends are fixed to the circuit. The split rings allow it to go past the vertical position, because they can 'disconnect' themselves from the circuit for a brief moment and make the 180 degree turn.

yeh tht will happen.......

 

[Lilly2318]

i

did u read this in any paper?
millibar is a unit for measuring pressure..it is a 100 pascals

it was stated in syllabus

 

[ZohaKhan]

by diffusion through stoma, by using the oxygen produced in photosynthesis, by the air in pores in the soil, and by directly through the outer air (as used by lower epidermal cells of leaf).
thats all, i guess.

ty

 

[exploded diper]

i

it was stated in syllabus

k ...but thts all i know bout it.....

 

[exploded diper]

what is the correct voltage against current graph.....and current against voltage....for ohmic conductors.....................

 

[Lilly2318]

k ...but thts all i know bout it.....

thnx

Physics :
(h) discuss the environmental and cost implications of underground power transmission compared to
overhead lines.

any help here?

 

[exploded diper]

thnx

any help here?

cost:
Any damage in underground lines is difficult to pinpoint and repair, and required repairs may take a couple of weeks to several months to complete. Conversely, damage to overhead lines is easy to locate and typically takes several hours or days to repair.
Underground transmission lines in a radial system require more cables to meet the same reliability as an overhead line. The additional components translate to a higher cost and can reduce overall system reliability.
The life expectancy of an underground line is about half that of an overhead line. so they need to be replaced more often...
environmental :
The environmental impacts of construction are greater for an under ground transmission line than for a comparable overhead line. however overhead cables can cause visual pollution...overhead lines may fall down due to some environmental condition .....a cooling system may be required for underground lines hence creating noise pollution.

 

[Awesome12]

isnt inertia responsible for the coil to keep on moving....

No it isn't

 

[FLRNAB]

"Underground transmission lines in a radial system require more cables to meet the same reliability as an overhead line."
"The life expectancy of an underground line is about half that of an overhead line. so they need to be replaced more often..."

Elaborate?

any help here?

More protected from weather conditions so less probability of power outage.

 

[***amd***]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_s12_ms_62.pdf
Q1 (c) (ii)
why cant we give reference to "more transpiration in in leaves in light because of more air spaces to cop with the more heat of sun" here?

 

[Mahnoorfatima]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_w07_qp_1.pdf
Question 6 ? Why cant the answer be b? As CO2 is entering into the test tube b, which is acidic in nature so the ph would fall below 7, no?
Question 13? I dont get this AT ALL! :'(
Question 28? The sun being the ultimate source of energy would provide energy to both the consumer and the producer. Why can't the answer be as as every living organism takes energy from sun independently, apart from the energy flowing from the producer to the consumer.

 

[Mahnoorfatima]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_s12_ms_62.pdf
Q1 (c) (ii)
why cant we give reference to "more transpiration in in leaves in light because of more air spaces to cop with the more heat of sun" here?

In this part they're asking about the 'observable differences' that you have mentioned in the previous part. So you gotta link your answer to that. I guess. Not sure.

 

[Awesome12]

s11 p41 physics

 

[exploded diper]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_w07_qp_1.pdf
Question 6 ? Why cant the answer be b? As CO2 is entering into the test tube b, which is acidic in nature so the ph would fall below 7, no?
no the plant is in a is respiring so tht is releasing co2 and thts y the colour of the tube would be yellow...and as for the other plant is is photosynthesizing and hence not releasing co2 or any alkaline substance so the tube would remain orange.....
Question 13? I dont get this AT ALL! :'(
the answer to this b......
Question 28? The sun being the ultimate source of energy would provide energy to both the consumer and the producer. Why can't the answer be as as every living organism takes energy from sun independently, apart from the energy flowing from the producer to the consumer.

have u seen any human ever making food by using suns energy directly....