The resistance change is a result of the antiferromagnet which acts to raise its magnetic coercivity and behaves as a " hard " layer, while the other is free ( unpinned ) and behaves as a " soft " layer.
32.
But beware, this only works in homework questions, in real life the resistance changes quite dramatically at different voltages because the temperature of the filament is different . "'Sp in ni ng Spark "'19 : 30, 9 May 2009 ( UTC)
33.
Selenium sensors however cannot measure low light accurately ( ordinary lightbulbs can take them close to their limits ) and are altogether unable to measure very low light, such as candlelight, moonlight, starlight etc . Silicon sensors need an amplification circuit and require a power source such as photoresistance, i . e . their electrical resistance changes proportionately to light exposure.
