1 / 8

ADV/TEC 5: Resonance

ADV/TEC 5: Resonance. Introductory mini-lecture. Resonance in physical systems. Mechanical: pendulum, Tacoma Narrows bridge Atomic transitions: frequency of photon matches the energy difference between two atomic levels

crwys
Download Presentation

ADV/TEC 5: Resonance

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. ADV/TEC 5: Resonance Introductory mini-lecture

  2. Resonance in physical systems • Mechanical: pendulum, Tacoma Narrows bridge • Atomic transitions: frequency of photon matches the energy difference between two atomic levels • Electrical: an LC circuit responds very sharply at a particular frequency Resonance is a property of systems that have a natural frequency of oscillation. For example:

  3. Parallel LCR circuit • Impedance of the capacitor decreases with frequency, so |iC| increases with frequency • Impedance of the inductor increases with frequency, so |iL| decreases with frequency

  4. LCR circuit at resonance • Impedance of inductor and capacitor in parallel: • At resonance ZL + ZC = jωL – j/ωC = 0, i.e.,|ZL|=|ZC |whenω2 =1/LC or • Ztotal is (theoretically) infinite, so net current = 0, i.e., iL= vL/ZL = –vC/ZC = –iC

  5. Vector representation • At resonance the vectors iL and iC are equal in magnitude but differ by 180⁰ in phase • Input and output voltages are equal

  6. Quality factor Q of a resonant circuit • f1 and f2 are the frequencies at which |v2/v1| = • Q = f0/(f2 – f1) measures the sharpness of the resonance • Q measures the ratio of energy stored to energy dissipated • Q is proportional to R, so need large R for high Q

  7. Quality factor Q of a resonant circuit

  8. Non-ideal inductor • The Q of the resonance is also affected by the resistance of the inductor RL • We represent RL as an equivalent parallel resistance R'L so R and R'L form a simple resistive voltage divider at resonance

More Related