How hot is it Current Voltage graphs Dependence

How hot is it? • Current – Voltage graphs • Dependence of resistance on heat • LDRs and thermistors

Current – Voltage graphs What is the component represented by this graph? A resistor at constant temperature I The gradient of the line is Draw another line I/V, but Lower resistance for a resistor with R = V/I lower resistance higher resistance gradient = 1/R Higher resistance V The current through a resistor (at constant temperature) is directly proportional to the voltage. The steeper the gradient, the lower the resistance

Filament lamp Is the filament lamp an Ohmic conductor? No, because the I – V graph is not a straight line, i. e. I is not directly proportional to V. The resistance of I the metal filament Hot inside the bulb increases as the Cool filament gets hotter V Hot As more current flows, the metal Write on your graph “hot” and filament“cool” gets in hotter, so its resistance the regions where increases. That’s why the graph the filament is hotter and gets flatter. cooler and explain why.

Diode Is the diode an Ohmic conductor? No, because the I – V graph is not a straight line, i. e. I is not directly proportional to V. I There is current flowing only when the voltage is positive. This means that almost no current flows if the voltage is applied in the reverse 0. 6 V V direction. 0. 6 V is. Point the voltage ataxis which on the V thethe diode starts working, i. e. the current voltage at which current flows through it. This voltage is called starts increasing. Activation Voltage.

Light Dependent Resistor LDR The resistance in LDRs depends on how much light shines on them. Resistance (Ω) When is the resistance higher? When it is darker! When is the resistance lower? When it is brighter! Write on the light intensity axis bright and dark in the appropriate places. Dark Bright Light intensity

Light Dependent Resistor LDR The resistance in LDRs depends on how much light shines on them. Resistance (Ω) Choose the right ending. As the light increases… 1. the current decreases. 2. the current stays the same. 3. the current increases. Dark Bright Light intensity

Thermistor (Temperature Dependent Resistor) The resistance in thermistors depends on the temperature. In what conditions is the resistan higher? In cool conditions! In what conditions is the resistan lower? In hot conditions! Resistance (Ω) Write on the temperature axis hot and cool in the appropriate places. Cool Hot Temperature

Thermistor (Temperature Dependent Resistor) The resistance in thermistors depends on the temperature. Resistance (Ω) Choose the right ending. As it gets cooler… 1. the current decreases. 2. the current stays the same. 3. the current increases. Cool Hot Temperature

Cell or Battery Thermistor Resistor Diode Filament lamp LDR

Cell or Battery Thermistor Resistor Diode Filament lamp LDR