Current Electricity 5 Question 6

6. A carbon resistance has a following color code. What is the value of the resistance?

(a) $5.3 M \Omega \pm 5 %$

(b) $64 k \Omega \pm 10 %$

(c) $6.4 M \Omega \pm 5 %$

(d) $530 k \Omega \pm 5 %$

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Solution:

  1. The value of a carbon resistor is given as

$$ R=A B \times C \pm D % $$

where, colour band $A$ and $B$ (first two colour) indicates the first two significant figures of resistance in Ohms.

$C$ (third colour) indicate the decimal multiplies and $D$ (fourth colour) indicates the tolerance in $%$ as per the indicated value. The table for colour code,

Colour code Values
$(\boldsymbol{A B})$
Multiplier
$(\boldsymbol{C})$
Tolerance
Black 0 $10^{0}$
Brown 1 $10^{1}$
Red 2 $10^{2}$
Orange 3 $10^{3}$
Yellow 4 $10^{4}$
Green 5 $10^{5}$
Blue 6 $10^{6}$
Voilet 7 $10^{7}$
Grey 8 $10^{8}$
White 9 $10^{9}$
Gold - - $\pm 5 %$
Silver - - $\pm 10 %$
No colour - - $\pm 20 %$

$\because$ Comparing the colours given in the question and table and writing in the manner of Eq. (i), we get

$$ \begin{aligned} R & =53 \times 10^{4} \pm 5 % \Omega \\ \text { or } \quad R & =530 \times 10^{3} \Omega \pm 5 % \text { or } R=530 k \Omega \pm 5 % \end{aligned} $$



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