OCR B: Advancing Physics Chapter 10 2.5 / 5 based on 2 ratings ? PhysicsCapacitorsA2/A-levelOCR Created by: CaraaCreated on: 13-06-13 17:15 Why do atoms become unstable? If they have too many neutrons, not enough neutrons or too much energy 1 of 14 What is radioactive decay? Whereb unstable atoms break down by releasing energy/particles until they reach a stable form 2 of 14 What is the activity of a source and what is it's equation? The number of particles decayed each seccond. A = -lamda.N 3 of 14 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 4 of 14 What is activity measured in? Becquerels (Bq) 5 of 14 What is the half life? The average time it takes for the number of undecayed atoms to halve 6 of 14 How can you find half life from a graph? You find half of the original activity/number of particles and read of the graph 7 of 14 What is the equation for decay? N = No.e^-lamda.t 8 of 14 What is the equation for half life? Half life = ln2 / lamda 9 of 14 What is the purpose of a capacitor? To store charge 10 of 14 What is capacitance measured in? Farads 11 of 14 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 12 of 14 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. 13 of 14 What is an equation for energy in a capacitor? E = 0.5QV or 0.5CV^2 14 of 14

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