The energy stored in a capacitor* To show that a charged capacitor stores energy Set up as shown. Close the switch to charge the capacitor. Remove the battery and connect the terminals together to the circuit. ‘short’ The bulb will as the capacitor discharges, showing that it stores energy. Common uses of capacitors The on a camera ‘flash’ Tuning into a station (for an explanation see the link on the page of thephysicsteacher.ie). Capacitance Allows alternating current (a.c.) to pass through it but blocks direct current (d.c.)*. Smoothing out variations in direct current. Used in circuits to only allow alternating current of a specific frequency to flow.* Quantity Symbol Unit Symbol of unit Q C Charge Coulombs I A Current Amps C F Capacitance Farads E N/C Electric Field Newton per Strength Coulomb Leaving Cert Physics Syllabus: Capacitance Content Depth of Treatment Activities STS Capacitors and Definition: = C Q/V capacitance Unit of capacitance. Parallel plate capacitor. Common uses of Demonstration that capacitors: Use of capacitance depends on tuning radios the common area, the • guns distance between the • plates, and the nature of smoothing • the dielectric. filtering. • Appropriate calculations. Energy stored in a capacitor. Charge capacitor–discharge through lamp or ½ d.c. motor. Use of = W CV 2 Appropriate calculations. Capacitors conduct a.c. but not – Demonstration. d.c.
The energy stored in a capacitor* To show that a charged capacitor stores energy Set up as shown. Close the switch to charge the capacitor. Remove the battery and connect the terminals together to ‘short’ the circuit. The bulb will as the capacitor discharges, showing that it stores energy. Common uses of capacitors The ‘flash’ on a camera Tuning into a station (for an explanation see the link on the Capacitance page of thephysicsteacher.ie). Allows alternating current (a.c.) to pass through it but blocks direct current (d.c.)*. Smoothing out variations in direct current. Used in circuits to only allow alternating current of a specific frequency to flow.* Quantity Symbol Unit Symbol of unit Charge Q Coulombs C Current I Amps A Capacitance C Farads F Electric Field Strength E Newton per Coulomb N/C Leaving Cert Physics Syllabus: Capacitance Content Depth of Treatment Activities STS Capacitors and capacitance Definition: C = Q/V Unit of capacitance. Parallel plate capacitor. Use of Demonstration that capacitance depends on the common area, the distance between the plates, and the nature of the dielectric. Appropriate calculations. Common uses of capacitors: • tuning radios • guns • smoothing • filtering. Energy stored in a capacitor. Use of W = ½ CV 2 Capacitors – conduct a.c. but not d.c. Charge capacitor–discharge through lamp or d.c. motor. Appropriate calculations. Demonstration.
20.%20Potential%20Difference%20and%20Capacitance.docx