parrellel resistors

Parallel resistors:

Parallel resistors:

We use the Formulae

1/RT = 1/R1 + 1/R2 +

1/R3 + ……1/Rn

Example:

20Ω

50Ω

40Ω

Example:

20Ω

50Ω

40Ω

1/RT = 1/R1 + 1/R2 + 1/R3 + ……1/Rn

Example:

20Ω

50Ω

40Ω

1/RT = 1/R1 + 1/R2 + 1/R3 + ……1/Rn1/RT = 1/20Ω + 1/50Ω + 1/40Ω

Example:

20Ω

50Ω

40Ω

1/RT = 1/R1 + 1/R2 + 1/R3 + ……1/Rn1/RT = 1/20Ω + 1/50Ω + 1/40Ω

On calculator use to enter fractionsa b/c

Example:

20Ω

50Ω

40Ω

1/RT = 1/R1 + 1/R2 + 1/R3 + ……1/Rn1/RT = 1/20Ω + 1/50Ω + 1/40Ω

On calculator use to enter fractions

ie: 1 20 1 50 1 40

a b/c

a b/c=

a b/ca b/c+ +

Example:

20Ω

50Ω

40Ω

1/RT = 1/R1 + 1/R2 + 1/R3 + ……1/Rn1/RT = 1/20Ω + 1/50Ω + 1/40Ω

On calculator use to enter fractions

ie: 1 20 1 50 1 40

1/RT = 19/200

a b/c

a b/c=

a b/ca b/c+ +

Example:

20Ω

50Ω

40Ω

1/RT = 19/200=+

Example:

20Ω

50Ω

40Ω

1/RT = 19/200To change back to decimal; =+

a b/c

Example:

20Ω

50Ω

40Ω

1/RT = 19/200To change back to decimal; 1/RT = 0.095

a b/c

Example:

20Ω

50Ω

40Ω

1/RT = 19/200To change back to decimal; 1/RT = 0.095 To get inverse

=+

a b/c

X-1

Example:

20Ω

50Ω

40Ω

1/RT = 19/200To change back to decimal; 1/RT = 0.095 To get inverse

RT = 10.52Ω=+

a b/c

X-1

Example:

20Ω

50Ω

40Ω

1/RT = 19/200To change back to decimal; 1/RT = 0.095 To get inverse

RT = 10.52ΩNote your answer should always be smaller than the smallest resistor=+

a b/c

X-1