ABSTRACT
At the end of this chapter you should be able to:
• recognize three common methods of resistor construction
• appreciate that electrical resistance depends on four factors
• appreciate that resistance R= ρl a , where ρ is the resistivity
• recognize typical values of resistivity and its unit
• perform calculations
• define the α
• recognize typical
• perform calculations • determine the resistor from its colour code
• determine the resistor from its letter and digit code
There is a wide range of resistor types. Four of the most common methods of construction are:
Many modern circuits use SMT resistors. Their manufacture involves depositing a film of resistive material such as tin oxide on a tiny ceramic chip.The edges of the resistor are then accurately ground or cut with a laser to give a precise resistance across the ends of the device. Tolerancesmay be as low as±0.02% and SMT resistors normally have very low power dissipation. Their main advantage is that very high component density can be achieved.
