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#### abd123

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##### Physics Questions.
« on: March 02, 2011, 07:48:13 pm »
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i came across with this question, i need help with this please . More questions might come soon

A nuclear scientist has prepared equal quantities of two radioisotopes, 211-Bi and 215-Bi. The
sample of Bismuth-211 initially has four times the activity of the bismuth-215 sample. The half-life of
bismuth-211 is equal to 2 min. Which of the following statements is true?

A) These isotopes have half-lives of 2 and 8min, respectively.
B) These isotopes have have half-lives of 8 and 2min, respectively.
C) These isotopes have identical half-lives because they contain the same element.
D) These isotopes have half-lives of 2 and 32 min, respectively.

#### /0

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##### Re: Physics Questions.
« Reply #1 on: March 03, 2011, 01:24:56 am »
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I would say A.
4 times the activity means 4 times the decay rate

Though I haven't done nuclear in a long time >_>

#### Killerkob

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##### Re: Physics Questions.
« Reply #2 on: March 03, 2011, 08:39:24 pm »
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I'd assume it would be something to do with the structure of the atom and how the electro-magnetic force keeps the electrons in orbit as opposed to colliding with the nuclei. Or possibly that beryllium-7 has a high ionising ability and therefore is more able to pass through matter, effectively 'dodging' the electrons.

Not too sure.
2009: Legal Studies
2010: English, Specialists Maths, Maths Methods, Physics, Music Styles
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#### schnappy

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##### Re: Physics Questions.
« Reply #3 on: March 03, 2011, 08:47:42 pm »
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The electron cloud (You can use that term literally or metaphorically I suppose) will repel the inbound electron, deflecting it.

I think.

#### schnappy

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##### Re: Physics Questions.
« Reply #4 on: March 05, 2011, 01:13:32 pm »
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And you want to do theoritical physics?

:S

#### /0

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##### Re: Physics Questions.
« Reply #5 on: March 05, 2011, 05:08:29 pm »
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And you want to do theoritical physics?

:S

Woah, he's only year 11... and anyway it never hurts to ask questions if you're unsure

#### /0

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##### Re: Physics Questions.
« Reply #6 on: March 14, 2011, 10:39:32 pm »
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Electrostatic force is given by $F = qE$, where $E$ is the electric field and $q$ is the charge of the object.

For the electron, we have $F$ and $q$, allowing us to solve for $E$.

We can then use $F=qE$ to find the force on the alpha particle.