Daily SprintSTART

1.What is Ohm’s Law?

2.A circuit is measured and has a voltage of 6.04v and current of 0.0004A. What is the total resistance in the circuit?

3.What is a capacitor? (make a prediction)

MSA Prep

Solve:

4 x 3 +2 x 5 – 6 ÷ 2 + 32

Capacitors

Capacitors

• Capacitors

• Charging the Capacitor

• Discharging the Capacitor

This presentation is intended to be used with Activity 4.2.5 Capacitors.

CapacitorsCapacitor: An electrical device used to store electrical charge

Symbol for Circuit Diagrams

DC

Capacitors

Capacitors allow DC 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.

DC_

+

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.

Charging the CapacitorGather a 12V power source, a lamp, and a 4700uF capacitor. Leave a spot for the capacitor but do not attach it yet.

You may need to wire more than one power source in the circuit in order to reach 12V.

Just as an LED is polarity-sensitive, many capacitors are too. Look for an indication on the capacitor to verify.

DC_

+

Charging the Capacitor

Plug in the capacitor.

What did the LED do after the capacitor was plugged in?

DC_

+

Discharging the CapacitorBuild a circuit with a pushbutton switch, a 6V / .5A (or higher) lamp, and a place for the charged capacitor to be placed.

Will the polarity of the capacitor affect this circuit? Explain.

Discharging the CapacitorPlug in the capacitor.

What did the lamp do?

Conclusion Questions

1.    Describe something other than the examples you’ve been given that you believe uses a capacitor and its function in the device.

2.    What do capacitors have to do with the dangers of older television sets?

Image Resources

Microsoft, Inc. (2009). Clip Art. Retrieved January 22, 2009, from http://office.microsoft.com/en-us/clipart/default.aspx