A2 Physics | Post your doubts here

[SkyPilotage]

can somebody please explain why have we divided the kinetic energy by 2 in Q2ii of November 2010 paper 43? we are required to calculate the temperature of the sample which contain both deteruim and protons and total kinetic energy is given then why dividing it by 2?

to find the speed of one of them only.

 

[miss irfan]

to find the speed of one of them only.

but we have to calculate temperature of the sample no?

 

[Idris]

Photoelectric effect is the process where electrons are emitted from a cold metal surface when electromagnetic radiation of sufficient frequency falls on it.
It is used to show the particulate nature of particles / electrons...

Brother it is essential that we use the particulate nature of photons not of electrons.

 

[SkyPilotage]

My question still remains. Why is the rate of emission of Alpha particles assumed to be constant?

half life is way too long.

 

[SkyPilotage]

Brother it is essential that we use the particulate nature of photons not of electrons.

Hmm im not sure I agree, cz electrons have a particele nature.
It is the electrons which have the wave-particle dualty.

 

[hassam]

cos the half life is like a million years........so in 2 days nothing will happen to activity.......cso it llll take such a long time to halve

 

[hassam]

but we have to calculate temperature of the sample no?

bt cnt it be like that they have different k.e

 

[hassam]

half life is way too long.

brother i want ot discuss wid u diodes graph.......i am not crystal clear abt them

 

[OakMoon!]

Can you try to solve this?
Am I only the one the ms is weird?'

A.C current w/ equation I=9.9sin(380t)
View attachment 9350

The ms is wrong for this question.

 

[optimistic]

half life is way too long.

cos the half life is like a million years........so in 2 days nothing will happen to activity.......cso it llll take such a long time to halve

how did you calculate it? i still don't understand!

 

[angelicsuccubus]

My question still remains. Why is the rate of emission of Alpha particles assumed to be constant?

because the rate of emission of alpha particles= half life..

what's the answer in the mark scheme anyway?

 

[prannoy]

no charge stored capaciotor plates store equal charge of opposite signs so no overall charge.............and energy is stored since there is a charge separation.....to separate charges like this work must have been done

thanx

 

[angelicsuccubus]

how did you calculate it? i still don't understand!

half life doesn't have to be long.. some elements have half life of minutes even (If I remember right from the practical.. )

 

[angelicsuccubus]

"Half-lives for various radioisotopes can range from a few microseconds to billions of years."

 

[angelicsuccubus]

cos the half life is like a million years........so in 2 days nothing will happen to activity.......cso it llll take such a long time to halve

that's like the most ridiculous answer I've heard all night.. think of some other reason, half life can be of a millisecond too.

 

[hassam]

oooooohhhhhhh man u have to SUGGGEST!!!

 

[SkyPilotage]

half life doesn't have to be long.. some elements have half life of minutes even (If I remember right from the practical.. )

If the emission seems to be constant, then the half life is very long.
The number given in the question is rate of emission i.e delta N / delta t, which I think is the activity.

 

[optimistic]

because the rate of emission of alpha particles= half life..

what's the answer in the mark scheme anyway?

Okay I got it. the answer in the marking scheme is the half-life of the source is very long or decay constant is very small. I think they mean that the half life is so huge that there will be a constant emission throughout the period before reaching half life.

 

[Idris]

for same substances the latent heat of vaporisation is greater then the latent heat of fusion.
esplain why??

In latent heat of fusion, the internal energy increases because the potential energy increase to break the bonds however increase kinetic energy is negligible as the separation is slow, where as in latent heat of vaporization work is done to expand the volume of liquid as well as increase the potential energy. I hope you get it.

 

[angelicsuccubus]

Okay I got it. the answer in the marking scheme is the half-life of the source is very long or decay constant is very small. I think they mean that the half life is so huge that there will be a constant emission throughout the period before reaching half life.

OH! its caus half life= 0.693/decay constant!