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# Physics

### Midterm

Question | Answer |
---|---|

Radioactivity | A substance that spontaneously emits energy |

Alpha Particle | same as a helium nucleus. 2 neutrons and 2 protons . Have large mass but can be stopped by paper. Radon is an alpha particle emitter |

Beta Particle | One of the neutrons within the nucleus is converted into a proton and an electron is ejected. Escaping electron is the beta particle |

Gamma Particle | High energy EM photon from the nucleus. IT is not in the visible part of the EM spectrum. |

Radioactive Half-Life | Time for half of the isotope to decay. Radioisotopes disintegrate into stable isotopes |

Hertz | Measurement of frequency. Occurrence/time. Cycle/S. Hz= 1/s. Hz= s^-1 |

Electromagnetic Spectrum | R.M.I.V.U.X.G |

Wave equation | Velocity= frequency (U symbol ) x wavelength (lamda L) |

Wave equation alternatives | C=U x L, F=U/L, L=C/U. For the pyramid, C is on top, U(frequency) bottom left, L(lambda) is bottom right |

Energy is the photon is _____ proportional to its frequency | directly. High frequency= high energy |

The energy of a photon is ______ proportional to its wavelength | inversely. Short wavelength= low energy |

Radiofrequency | Usually described in terms of frequency (Hz). Rf waves have very low energy and long wavelength. Used in MRI. Overlap on the EM spectrum with microwaves. |

Ionizing Radiation | Characterized by the energy contained in a photon. Much higher energy levels than RF or visible light photons |

Ionizing Radiation Attenuation | Reduction in intensity resulting from SCATTER and ABSORPTION. Radiopaque (Absorb photons). Radiolucent/Radioparent (gowns, tape, hair.) Absorbing so there is LESS photons. |

Planck's Quantum Equation | E=hU. E is the photon energy. h is planck's constant, and U is the photon frequency in hertz |

Exponent, decimal rule | Each time we move the decimal point one place to the left, the exponent increases by 1. |

Created by:
Djneil12