# OCR B: Advancing Physics Chapter 10

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• Created by: Caraa
• Created on: 13-06-13 17:15
Why do atoms become unstable?
If they have too many neutrons, not enough neutrons or too much energy
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Whereb unstable atoms break down by releasing energy/particles until they reach a stable form
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What is the activity of a source and what is it's equation?
The number of particles decayed each seccond. A = -lamda.N
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What is the decay constant?
The probability that a nucleus will decay in a certain time. The bigger it is the more likely the decay so the faster the rate of decay
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What is activity measured in?
Becquerels (Bq)
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What is the half life?
The average time it takes for the number of undecayed atoms to halve
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How can you find half life from a graph?
You find half of the original activity/number of particles and read of the graph
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What is the equation for decay?
N = No.e^-lamda.t
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What is the equation for half life?
Half life = ln2 / lamda
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What is the purpose of a capacitor?
To store charge
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What is capacitance measured in?
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What is the equation for capacitance and what do the terms represent?
C = Q/V C is capacitance, Q is charge in coulombs, V is p.d
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How do capacitors store energy?
Charge builds up on the plates of the capacitor. Electrical energy provided by the battery is stored by the capacitor.
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What is an equation for energy in a capacitor?
E = 0.5QV or 0.5CV^2
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## Other cards in this set

### Card 2

#### Back

Whereb unstable atoms break down by releasing energy/particles until they reach a stable form

### Card 3

#### Front

What is the activity of a source and what is it's equation?

#### Back ### Card 4

#### Front

What is the decay constant?

#### Back ### Card 5

#### Front

What is activity measured in?

#### Back 