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# A2 physics - Cyclotron Question Help needed! watch

1. How do I do question 10 part a and b?

What formulas do I use?

2. PART A:

In a cyclotron, a particle is accelerated whenever it passes between the Ds, as each D is oppositely charged and as a result there is an electric field between the Ds. Whenever a charged particle (such as a proton) passes through an electric field, work is done on the particle causing it to accelerate.

Potential difference in electricity is defined as the work done per unit charge, i.e.

When rearranged, this gives .

We can use this formula to calculate the energy gained by the proton due to passing through the electric field ONCE, using the constant for the charge of a proton, and the potential difference value given in the question.

Number of times passing between D's

PART B:

The charge on each D in a cyclotron is always opposite to the charge on the other D. These charges alternate with the given frequency in the question. As frequency is the reciprocal of the time period, i.e.

We can rearrange to give:

And using the value for frequency given in the question, we can determine the period of time spent in one cycle by the proton.

Now we know the number of times the proton crosses the field between the Ds, because we calculated this in part A. But remember that in one cycle of the cyclotron, the proton will actually cross the field between the Ds twice, so we need to half this number. This gives us:

Time spent in cyclotron
or
Time spent in cyclotron

Where is the time spent in one cyclotron cycle, is the number of times crossing the electric field between the Ds of the cyclotron, and is simply .

Take care when converting to/from , and watch out for your SI prefixes for frequency and energy!
3. (Original post by The_Big_E)
PART A:

In a cyclotron, a particle is accelerated whenever it passes between the Ds, as each D is oppositely charged and as a result there is an electric field between the Ds. Whenever a charged particle (such as a proton) passes through an electric field, work is done on the particle causing it to accelerate.

Potential difference in electricity is defined as the work done per unit charge, i.e.

When rearranged, this gives .

We can use this formula to calculate the energy gained by the proton due to passing through the electric field ONCE, using the constant for the charge of a proton, and the potential difference value given in the question.

Number of times passing between D's

PART B:

The charge on each D in a cyclotron is always opposite to the charge on the other D. These charges alternate with the given frequency in the question. As frequency is the reciprocal of the time period, i.e.

We can rearrange to give:

And using the value for frequency given in the question, we can determine the period of time spent in one cycle by the proton.

Now we know the number of times the proton crosses the field between the Ds, because we calculated this in part A. But remember that in one cycle of the cyclotron, the proton will actually cross the field between the Ds twice, so we need to half this number. This gives us:

Time spent in cyclotron
or
Time spent in cyclotron

Where is the time spent in one cyclotron cycle, is the number of times crossing the electric field between the Ds of the cyclotron, and is simply .

Take care when converting to/from , and watch out for your SI prefixes for frequency and energy!
Bro I really appreciate the thorough and insightful answers even my class teachers don't explain a question in such detail and context thanks. Really helped me.

Thanks again!
4. No problem, I get your struggle. Learning physics with a teacher that can't explain really sucks. :P

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