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[Ghost Of Highbury]

Hey, please can someone explain how you work out Q6)a)iii) for w09.  Link for paper is: http://www.freeexampapers.us/IGCSE/Physics/CIE/2009%20Nov/0625_w09_qp_31.pdf

F = pressure * area.

b4 weights : 1.05 × 105 × 5.0 × 10^-3 = 525N

after weights : 1.4 × 105 × 5.0 × 10^-3 = 700N

700-525 = 175N

[2010]

i cant understand 1 thing...
When gamma cannot be stopped by lead why is it stored in lead containers.....I know that lead reduces the intensity of gamma but it doesn't stop it does it?

[Ivo]

F = pressure * area.

b4 weights : 1.05 × 105 × 5.0 × 10^-3 = 525N

after weights : 1.4 × 105 × 5.0 × 10^-3 = 700N

700-525 = 175N

OK thanks a lot A@di, very clear explanation.  Just wanted to know how to explain, for same paper and question, part b)i), I know the volume increases when temp. increases, but is it because gas molecules expand and so become less dense, so occupy larger volume, or is it because kinetic energy of mol. are greater, therefore more hits with molecules.

[M'i'D'o]

hey everyone....
what is the GREATEST danger if there is a wire kept uninsulated in a room ??
is it fire or electric shock or any other ??
plz reply fast

[ambitious94]

Can anyone plzzzzzzzzzzzzzzzzzzzz plzzzzzzzzzzzzzzz explain me June 09 Q 11 b!!!
Whoever predicted we're screwed wasnt lying! XD
I havent actually studied the portion! UGHHHH

[Ghost Of Highbury]

OK thanks a lot A@di, very clear explanation.  Just wanted to know how to explain, for same paper and question, part b)i), I know the volume increases when temp. increases, but is it because gas molecules expand and so become less dense, so occupy larger volume, or is it because kinetic energy of mol. are greater, therefore more hits with molecules.

the MOLECULES dont expand, their intermolecular SPACE increases because as they have more KE.

[Ivo]

the MOLECULES dont expand, their intermolecular SPACE increases because as they have more KE.

OK, so let's clear this up:

Expansion: is due to the expansion of gas (molecules get further apart) and forces the piston out, as the volume increases.

Pressure: an increase in pressure is due to molecules gaining more ke and so hit the sides more frequently and with more force, so pressure increases.

However, I don't know how to explain the relationship of volume with pressure for constant temperature.  Please explain.

[Ghost Of Highbury]

Can anyone plzzzzzzzzzzzzzzzzzzzz plzzzzzzzzzzzzzzz explain me June 09 Q 11 b!!!
Whoever predicted we're screwed wasnt lying! XD
I havent actually studied the portion! UGHHHH

SHould be perpendicular to the magnetic field. Negative plate opposite the deflection. So that the alpha particle gets attracted to the negative and cancels the deflection..

@Ivo = When pressure increases , volume decreases. Consider a syringe, if u apply pressure, the volume of air in the syringe decreases...inversely propotional

[Ghost Of Highbury]

hey everyone....
what is the GREATEST danger if there is a wire kept uninsulated in a room ??
is it fire or electric shock or any other ??
plz reply fast

Electric shock?

[Malak]

Q9 part c All

thx

http://www.freeexampapers.us/IGCSE/Physics/CIE/2009%20Nov/0625_w09_qp_32.pdf

[MasterMath]

can someone verify this for me ? The Advantage of using a CRO over a Voltmeter is because CRO produces more accurate reading as it consumes less curent?

FAST PLEASE

[Baladya]

http://www.freeexampapers.us/IGCSE/Physics/CIE/2009%20Nov/0625_w09_qp_31.pdf

Q6)b)ii) Why does it stay the same? Isnt it supposed to be constant?

Thanks

[Ghost Of Highbury]

can someone verify this for me ? The Advantage of using a CRO over a Voltmeter is because CRO produces more accurate reading as it consumes less curent?

FAST PLEASE

yes, by adjusting the time-base and the y-gain, more accurate results.

[the_grim_reaper]

Electric shock?

Has to be. It was an MCQ in today's paper 1. I did electric shock..

Anyway, I've got just one question today, like you know when we heat something, after we stop, we take the greatest temperature rise. In question 5 (c), November 2008, why are we subtracting 16.3 from 2.1?? I mean will the heater's heat not melt more ice after the it's switched off?? (If this question has been answered, just tell me the page number)

Secondly, say if we're asked to find the latent heat of vaporisation of water, so we calculate the energy given AFTER it reaches the boil right?? Similar in ice like we calculate the amount of heat given AFTER it melts a little??? And like can a joule meter be used in a circuit like say we're using a heater. As soon as the water starts to boil, you switch on the joule meter. Basically, what I want to know is that will current flow through if it is not switched on? (So we can switch it on at any time and calculate the energy only for that interval??)

[Adzel]

Electric shock?

yes...