Electronic Components

Many electronic components are used to control the current and potential difference in a circuit. The current through a component can be varied using either a variable resistor or a potential divider.A variable resistor (rheostat) is connected in series with the component. Changing its resistance changes the current, but the current and p.d. across the component can never be reduced to zero.A potential divider, or potentiometer, is connected across the supply, with the component connected between the sliding contact and one end. Moving the slider varies the p.d. across the component continuously from zero up to the full supply voltage.Other important components include the thermistor, whose resistance falls as its temperature rises, the light-dependent resistor (LDR), whose resistance falls as the light intensity increases, and the semiconductor diode, which lets current pass easily in one direction (forward bias) but hardly at all in the other (reverse bias).