ST09 – Capacitor 1 Capacitor Lecturer: Smilen Dimitrov Sensors Technology – MED4.
capacitor
description
Transcript of capacitor
Function :
• Capacitors can store and then release electrical energy .
• The value of a capacitors is often measured in micro-farads .
• The amount of energy stored by the capacitor depends on :
How much charged is moved on to the plates .
• The large the capacitance , the more charge the capacitor stores for each volt applied across its plates . In fact :
• Capacitance = charge / voltage • C = Q / V
Complete the table :t(s) I(µ A) Q=It
(µC )V ( v) C = Q / V
(µ F)0 60 0
10 60 1.2
20 60 2.4
30 60 3.6
40 60 4.8
Questions :
• Q1:What happens to the switch in position A?
• Q2:What happens to the switch in position B?
• Q3:Where did this energy come from ?
• The p.d. across the capacitor and the size of its capacitance , both affect the energy stored .
• Energy stored =0.5Xcapacitance X (voltage)2
W = 0.5 X C X V2 OR W = 0.5 X Q X V
Q1
• A capacitor is charged using a current of 20µA from a 5volts supply .After 55s it is fully charged.
• Calculate :• A. Q?• B. C?• C. W?
More Qs.
• http://electronics.howstuffworks.com/solid-state-electronics-channel.htm
http://us.c2w.com/quizzes/45045-capacitor-quiz
Here are 3 facts that you should know for
• The p.d. across each capacitors is the same & equal to V .
• The total Q is the sum Q = Q1+Q2• The total C is the sum C = C1+C2
Q = C V
Here are 3 facts that you should know for
• The Q. across each capacitors is the same & equal to Q .
• The total V is the sum V= V1+V2• The total C is the sum 1/C = 1/C1+ 1/C2
Capacitors in Parallel
Capacitors in sires
V Same V = v1+v2
Q Q = Q1+Q2 Same
C C =C1+C2 1/C = 1/C1 + 1/C2
Qs.
• Q1: Calculate the charge on each capacitor in this diagram :
• If :• V=5volt• C1=500 micro farad C2=300 micro farad