Temperature, Heat and Internal Energy

Temperature

The degree of hotness

Temperature, Heat and Internal Energy

Temperature Scales

(1) Ice point 0oC (melting ice)

(2) Steam point 100oC (boiling water)

Celsius Scale

Temperature, Heat and Internal Energy

Kelvin Scale

Ice pt : 273 KSteam pt : 373 K

1K = 1oC

T(in K) = T (in oC) + 273

Absolute zero-273oC or 0 K

Temperature, Heat and Internal Energy

Particle motion and Temperature

Examine the relationship HERE

Temperature

Particles move faster

Average K.E. increases

Temperature, Heat and Internal Energy

ThermometerInstrument to measure temperature

Common type of thermometer:

Liquid-in-glass thermometer(1) mercury-in-glass(2) alcohol-in-glass

Temperature, Heat and Internal Energy

Clinical Thermometer

Thermal Expansion in liquid

Around 37oC

Narrow bend : avoid running back

Temperature, Heat and Internal Energy

Rotary Thermometer

Thermal Expansion in solid

About –40 to 60oC (small range)

Temperature, Heat and Internal Energy

Thermocouple Thermometer

Voltage / current

-200oC to 1700oC (very large range)

Industry (ovens / furnaces)

Temperature, Heat and Internal Energy

Resistance ThermometerResistance, Current

-200oC to 1200oC

Industry

Temperature, Heat and Internal Energy

Thermistor Thermometer

Resistance, Current

Up to hundreds

Home use

Not very accurate

Temperature, Heat and Internal Energy

Calibration of a Thermometer

Click HERE to see the calibration of a thermocouple thermometer

Temperature, Heat and Internal Energy

Internal energy

K.E. + P.E.

Force between particlesDistance P.E. Solid < liquid < gas

Motion of particles

T increases K.E. increases

T oC

Temperature, Heat and Internal Energy

Heat

TA > TB

HeatingA B

Temperature, Heat and Internal Energy

REMARKS ON HEATING

1. Heating ends when TA = TB

2. Energy Transfer:(a) Doing work - force(b) Heating – temp. diff.

3. Power of heating?* P = E / t* in W, kW* Joulemeter / kWh meter

and stop watch