Question 1
Three resistors X, Y and Z have the following colour codes:
- State the values of resistors X, Y and Z.
- State two differences between Carbon and Wire-wound resistors
Observation
The expected answers were:
- Values of Resistors X, Y and Z
X (Ω): 220 ± 10% OR 22 x 101 ± 10%
Y (Ω): 470 ± 5% OR 47 x 101 ± 5%
Z (Ω): 560 OR 56 x 101
- Differences between Carbon and Wire wound resistors
- Wire wound resistor is used for power rating above 5W while carbon resistor is used for power rating less than 5W.
- Carbon resistor uses colour codes for representing values while wire wound values are printed on the body.
- Wire wound resistor is made from ceramic and wire while carbon resistor is made from carbon and wire.
- Carbon resistor is suitable for high frequency circuits while wire wound resistor is not.
- Carbon resistor has low temperature coefficient while wire wound resistor has high temperature coefficient.
- Carbon resistor of less than 2Ω is difficult to produce while wire wound resistor is easy to produce for very low values.
Many of the candidates that attempted this question stated the coded resistors values correctly and the differences between the resistor types. However, some of them had problem with tolerance and difference between the resistor types.