Capacitor valu

es

Working out the capacitance

Cera

mic

dis

c ca

paci

tors

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.

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.

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.

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.

Now it's your turn.

Look at the capacitor on the left, what value is

it? Press next to check

your answer.

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.