1. Capacitor values Capacitor values Working out the capacitance

2. Ceramic disc capacitors  The most common two types of capacitors are ceramic disc and electrolytic capacitors (as shown left). The ceramic disc capacitors cover the smaller values, whilst the electrolytic capacitors have larger capacitance's.  It's easy to work out the value of an electrolytic capacitor as it is printed in on the side without being coded. However the ceramic disk capacitors are a little harder to work out, this lesson will teach you about ceramic disc values.

3.  Looking at the ceramic disc capacitor (left) you will see it has a 3 digit number printed on it (101).  The first two digits, in this case the 10 give us the first part of the value. The third digit gives us the number of extra zeros, in this case 1 extra zero.  So we have 10 with 1 extra zero. Thus the value is 100. Ceramic disc capacitor codes are always measured in pico Farads or pF. So we have a 100pF capacitor.

4.  On the capacitor (left) we now have the number 103. So as before we have 10, but now with three extra zeros. So it's value is 10,000. Again this is measured in pF, so the capacitor is a 10,000 pF capacitor.  As this involves writing out several zeros, the capacitance can be expressed in nano Farads or nF for short.  Where 1000 pF = 1 nF.  So our 10,000 pF capacitor can be better written as a 10 nF capacitor.

5.  When a capacitor can be written without needing any extra zeros to be added to the value, the third digit is not printed.  If the capacitor only has two digits on it, like the one shown left then that is its value in pF.  So this capacitor is a 10 pF capacitor.

6.  Now it's your turn. Look at the capacitor on the left, what value is it?  Press next to check your answer.

7.  Well done if you worked out that it is a 47 nF capacitor.  If you decided it was a 47,000 pF that is the same value but it is easy to write as a 47 nF.  Return to the interactive learning & test zone to check out your knowledge on capacitor values with a multiple choice test.