OCR Physics G485 - June 2013 Unit 5 (OFFICIAL THREAD)

Thanks a lot George,

Original post by Picture~Perfect

I appreciate the effort you've made to answer these questions for them but I think it would be sensible to give them chance a to answer some of these questions themselves as many are fairly basic and can be found easily either from the textbook or online.
No offence to you, I just feel that it impossible to learn by answering basic questions and reading others answer. I don't think we are doing them any favours.

I search them but most of them wasn't sure what to put on my notes that's why I asked.
No offence to you, but if I asked a question it means I need help, it's not like I posted these questions and never tried to answer them.#
Thanks for at least worry about our/my learning.

(edited 10 years ago)

Reply 323

Original post by GeorgeL3

....

For the first one, how does it answer the question.

Reply 324

Lilmzbest

Original post by Namod

For the first one, how does it answer the question.

The importance is in making sure all the ultrasound isn't just reflected off (the third point). The other points are an explanation of how it works, i think that a question on acoustic impedance would probably be 2/3 marks so they would want an explanation of how it works :smile:

Reply 325

Original post by Lilmzbest

The importance is in making sure all the ultrasound isn't just reflected off (the third point). The other points are an explanation of how it works, i think that a question on acoustic impedance would probably be 2/3 marks so they would want an explanation of how it works :smile:

Original post by GeorgeL3

I guess it's only the first part that answers the question. Impedance matching is important because otherwise most of the ultrasound used is reflected so there isn't enough to effectively scan the patient. The rest is a procedure for how impedance matching is done.

ok thanks

Reply 326

Picture~Perfect

19

Original post by Namod

Thanks a lot George,

I search them but most of them wasn't sure what to put on my notes that's why I asked.
No offence to you, but if I asked a question it means I need help, it's not like I posted these questions and never tried to answer them.#
Thanks for at least worry about our/my learning.

I realise if you're asking a question you require help and I meant no offence, it seemed as if you weren't helping yourself and Physics in particular isn't a subject that you can pass simply by rote learning answers, you need to understand the principles. Perhaps I over steeped the mark and if so I apologise I was simply trying to get people to understand that you need to try answering things yourself before turing for help if you wish to learn.

(edited 10 years ago)

Reply 327

OP

Original post by Picture~Perfect

I appreciate the effort you've made to answer these questions for them but I think it would be sensible to give them chance a to answer some of these questions themselves as many are fairly basic and can be found easily either from the textbook or online.
No offence to you, I just feel that it impossible to learn by answering basic questions and reading others answer. I don't think we are doing them any favours.

I agree with this to be honest, as I had to learn the hard way Physics is not History. You have to do questions frequently and keep marking yourself! This is just tough love.

From marking my own Questions I realised I wasn't in the same Frame of mind I am in for C3/C4 as I am when I do Physics which is so wrong! You really have to do questions by yourself. It's long, and its tough but it has to be done. I am going to re-do all the Questions I did on Ultrasound because I kept forgetting to do 2x the distance. My teacher thought I was a dumb-ass pardon my French.

It's the only way to get the Top Grades.

(edited 10 years ago)

Reply 328

Gingerdom

I'm fine on nearly all the module except the electromagnetic induction stuff and some of the harder electric fields stuff, has anyone got any hints to help remember this stuff?
Really need around 90% to get the A* some any ideas would be welcome

Reply 329

singh224

Can someone pelase explain the Piezoelectric effect as I can't find the exact answer anywhere.

Thanks

Reply 330

GeorgeL3

5

Original post by singh224

Can someone pelase explain the Piezoelectric effect as I can't find the exact answer anywhere.

Thanks

The piezoelectric effect is when a material expands or contracts when a potential difference is applied across it.
In ultrasound imaging they use piezoelectric crystals with an AC source to produce ultrasound waves.

Reply 331

singh224

Original post by GeorgeL3

The piezoelectric effect is when a material expands or contracts when a potential difference is applied across it.
In ultrasound imaging they use piezoelectric crystals with an AC source to produce ultrasound waves.

Thanks, in the book there is just some random complicated method shown which will give no marks in the exam :/

Reply 332

OP

Original post by GeorgeL3

...

Lol ironically all those notes George put up I am going to use now I'm doing Module 5. :colondollar:

Can someone please explain why there are no values for Hubbles Constant etc etc in the Datasheet? It has me very confused, and the values of Parsec?

Are we supposed to know them off the top of our heads??? :smile:

Reply 333

blossomx

20

Original post by Better

Lol ironically all those notes George put up I am going to use now I'm doing Module 5. :colondollar:

Can someone please explain why there are no values for Hubbles Constant etc etc in the Datasheet? It has me very confused, and the values of Parsec?

Are we supposed to know them off the top of our heads??? :smile:

We need to know the value for parsec, 1 light year and the astronomical unit.

Hubble's constant isn't known exactly, it's only estimated but it's around 70. From what I've seen we're always given the value but we need to know how to convert it to seconds.

Reply 334

Lilmzbest

Original post by Better

Lol ironically all those notes George put up I am going to use now I'm doing Module 5. :colondollar:

Can someone please explain why there are no values for Hubbles Constant etc etc in the Datasheet? It has me very confused, and the values of Parsec?

Are we supposed to know them off the top of our heads??? :smile:

Pretty much yeah...it's annoying :tongue:

what's more annoying is that they give the value for a light year and that's easy to work out :tongue:

Reply 335

Original post by LeaX

We need to know the value for parsec, 1 light year and the astronomical unit.

Hubble's constant isn't known exactly, it's only estimated but it's around 70. From what I've seen we're always given the value but we need to know how to convert it to seconds.

Original post by Better

Lol ironically all those notes George put up I am going to use now I'm doing Module 5. :colondollar:

Can someone please explain why there are no values for Hubbles Constant etc etc in the Datasheet? It has me very confused, and the values of Parsec?

Are we supposed to know them off the top of our heads??? :smile:

1 light year is in the datasheet.
From the questions i done for parsec and astronomical unit, the values are given under the questions, when you need them. :s-smilie:

Reply 336

OP

Original post by Namod

1 light year is in the datasheet.
From the questions i done for parsec and astronomical unit, the values are given under the questions, when you need them. :s-smilie:

Are you sure?

I don't want to learn them but I don't want to lose any marks.

Lol I like how all of you guys have said different things. I'm even more confused. :s-smilie:

George Get in here!

Reply 337

blossomx

20

Original post by Namod

1 light year is in the datasheet.
From the questions i done for parsec and astronomical unit, the values are given under the questions, when you need them. :s-smilie:

I've seen a question where you are given a value for Hubble's constant in kms-1Mpc-1 and asked to convert it into seconds without being told the value for 1 pc.

Reply 338

OP