Capacitors Capacitors Gateway To Technology® Unit 6 – Lesson 6.2 – Electronics Capacitors

Capacitors Capacitors Charging the Capacitor Discharging the Capacitor Gateway To Technology® Unit 6 – Lesson 6.2 – Electronics Capacitors Capacitors Charging the Capacitor Discharging the Capacitor This presentation is intended to be used with Activity 6.2.5 Capacitors.

Symbol for Circuit Diagrams Capacitors Gateway To Technology® Unit 6 – Lesson 6.2 – Electronics Capacitors Capacitor: An electrical device used to store electrical charge Symbol for Circuit Diagrams Use this slide to fill in schematic symbols page. or

Capacitors Gateway To Technology® Unit 6 – Lesson 6.2 – Electronics Capacitors Capacitors allow current to flow through a circuit as they fill with a charge. When the capacitor’s voltage supply matches the power source, current stops flowing. _ + Think of a capacitor like a water tower – a water tower stores water for later use (it even resembles – distantly – a water tower)

Capacitors Made of two layers of conductor and a layer of insulator. Gateway To Technology® Unit 6 – Lesson 6.2 – Electronics Capacitors Made of two layers of conductor and a layer of insulator. Electrolytic Capacitors Capacitance, measured in Farads (F) 1 F = 6.28 x 1018 electrons 1 µF = 6.28 x 10-6 electrons There are many kinds of capacitors, but they all do the same thing: STORE ELECTRICITY. The simplest capacitor is two CONDUCTORS separated by an INSULATING MATERIAL called the dielectric. The dielectric can be paper, plastic film, mica, glass, ceramic, air, or a vacuum. The conducting plates can be aluminum discs, aluminum foil, or a thin film of metal applied to opposite sides of a solid dielectric. The conductor-dielectric-conductor sandwich can be rolled into a cylinder or left flat. Capacitors come in all shapes and sizes. Some are called electrolytic, and have POSITIVE and NEGATIVE legs which must be connected the right way in a circuit. However, usually those with a small value (less than 1 μF) can be connected any way in the circuit. The ability to store electrons is known as CAPACITANCE and is measured in FARADS. A 1-farad capacitor connected to a 1 volt supply will store 6,280,000,000,000,000,000 (6.28 x 1018) electrons! Most capacitors have much smaller values. Small capacitors are specified in PICOFARADS (trillionths of a farad) and larger capacitors are measured in MICROFARADS or µF (millionths of a farad). 1 farad = 1 F 1 microfarad = 1 μF = 10-6F = 0.000 0001 F 1 picofarad = 1 pF = 10-12F = 0.000 000 000 001 F In our labs, we will be using microfarad (μF) capacitors. 

Capacitors Gateway To Technology® Unit 6 – Lesson 6.2 – Electronics Capacitors Stored energy in the capacitor is released in a quick burst unless slowed by resistance. Capacitors are found in almost all electronic devices. They store energy, provide quick bursts of power, even out power if there is a small loss, etc. Capacitors are used for the flash in cameras. Capacitors may retain a charge long after power is removed from a circuit; this charge can cause dangerous or even potentially fatal shock or damage connected equipment. For example, even a device such as a disposable camera flash unit powered by a 1.5 volt AA battery contains a capacitor which may be charged to over 300 volts. This is easily capable of delivering a shock.  Can be found in anything with an amplifier, tasers, starting motors, and many other uses.

Capacitors Gateway To Technology® Unit 6 – Lesson 6.2 – Electronics Charging Circuit Draw a schematic diagram of the following charging circuit, which includes a capacitor, a push switch, a LED, powered by a 6V DC power supply. Just as an LED is polarity-sensitive, many capacitors are too. Look for an indication on the capacitor to verify.

Capacitors Gateway To Technology® Unit 6 – Lesson 6.2 – Electronics Discharging Circuit Draw a schematic diagram of the discharging circuit with a pushbutton switch, a LED, and a place for the charged capacitor to be placed. Will the polarity of the capacitor affect this circuit? Explain.

Charging the Capacitor Capacitors Gateway To Technology® Unit 6 – Lesson 6.2 – Electronics Charging the Capacitor Place the smallest capacitor in the circuit. Push the switch, completing the circuit. What did the LED do after the capacitor was plugged in? The light should be on briefly as the capacitor charges. Once the capacitor is charged, the light will be out. The capacitor has polarity, and must be hooked up negative side towards the negative power. (Negative leg of the capacitor to the positive leg of the LED.)

Discharging the Capacitor Capacitors Gateway To Technology® Unit 6 – Lesson 6.2 – Electronics Discharging the Capacitor Plug the capacitor into the discharge circuit. Press the push switch. What did the LED do? This is essentially how a camera flash operates. Repeat the charge and discharge with the other capacitors provided.

Capacitors Gateway To Technology® Unit 6 – Lesson 6.2 – Electronics Image Resources Microsoft, Inc. (2009). Clip Art. Retrieved January 22, 2009, from http://office.microsoft.com/en-us/clipart/default.aspx