Resistivity and Ohm's law

Ohm’s law

obeyed when current is directly proportional to potential difference across its ends

ohmic

obeys ohms law

non-ohmic

doesnt obey ohms law

lamp I-V characteristic

metallic conductor I-V characteristic

diode I-V characteristic

NTC thermistor

negative temperature coefficient…resistance decreases when temperature increases

LDR

light dependent resistor…resistance decreases when light intensity increases

length and resistance

directly proportional

resistance and cross-sectional area

inversely proportional

resistivity

a measure of a material’s electrical resistance

resistivity formula

R=pl/A