Class 9th Physics Chapter 8 Question Answer

Complete Notes of Class 9th Physics Chapter 8 Question Answer Thermal Properties of Matter Numericals of 9th Class Physics Urdu Medium written by Sir Fahad Abbas Suib. These computerized notes are very helpful in the preparation of Thermal Properties of Matter Numericals for students of the Class 9th Physics Chapter 8 Question Answer these are according to the paper patterns of all Punjab boards.

• Important Values and Important Formulas
• Thermal Properties of Matter Exercise Numericals with Solutions in Urdu 
• LIQUID-IN-GLASS THERMOMETER: A liquid-in-glass thermometer has a bulb with a long capillary tube of uniform and fine bore. A suitable liquid is filled in the bulb. When the bulb contacts a hot object, the liquid in it expands and rises in the tube. The glass stem of a thermometer is thick and acts as a cylindrical lens. This makes it easy to see the liquid level in the glass tube.
• Bulb Mercury thread Temperature scale Mercury Glass tube.
• Mercury Glass tube Mercury freezes at-39 °C and boils at 357 °C. It has all the thermometric properties listed above. Thus mercury is one of the most suitable thermometric material. Mercury-in-glass thermometers are widely used in laboratories, clinics and houses to measure temperatures in the range from -10 °C to 150 °C.
• LOWER AND UPPER FIXED POINTS: A thermometer has a scale on its stem. This scale has two fixed points. The lower fixed point is marked to show the position of liquid in the thermometer when it is placed in ice. Similarly, upper fixed point is marked to show the position of liquid in the thermometer when it is placed in steam at standard pressure above boiling water.
• Scales of temperature class 9: A scale is marked on the thermometer. The temperature of the body in contact with the thermometer can be read on that scale. Three scales of temperature are in common use. These are:
• (i) Celsius scale or centigrade scale, (ii) Fahrenheit scale, (iii) Kelvin scale
• CONVERSION OF TEMPERATURE FROM ONE SCALE INTO OTHER TEMPERATURE SCALE:
• From Celsius to Kelvin Scale: The temperature T on Kelvin scale can be obtained by adding 273 in the temperature C on Celsius scale. Thus    T(K) = 273 + C
• FROM KELVIN TO CELSIUS SCALE: The temperature on Celsius scale can be found by subtracting 273 from the temperature in Kelvin Scale. Thus   C = T(K) - 273
• FROM CELSIUS TO FAHRENHEIT SCALE: Since 100 divisions on Celsius scale are equal to 180 divisions on Fahrenheit scale. Therefore, each division on Celsius scale is equal to 1.8 divisions on Fahrenheit scale. Moreover, 0°C corresponds to 32°F.    F = 1.8 C + 32.
• Specific heat capacity class 9: The specific heat of a substance is defined as; Specific heat of a substance is the amount of heat required to raise the temperature of 1 kg mass of that substance through 1K.
• Water has a large specific heat capacity. For this reason, it is very useful in storing and carrying thermal energy due to its high specific heat capacity. The cooling system of automobiles uses water to carry away unwanted thermal energy. In an automobile, large amount of heat is produced
• Heat capacity class 9: How much heat a body can absorb depends on many factors. Here we define a quantity called heat capacity of a body as: "Heat capacity of a body is the quantity of thermal energy absorbed by it for one kelvin (1 K) increase in its temperature".
• Latent heat of fusion class 9: When a substance is changed from solid to liquid state by adding heat, the process is called melting or fusion. The temperature at which a solid starts melting is called its fusion point or melting point. When the process is reversed i.e. when a liquid is cooled, it changes into solid state. The temperature at which a substance changes from liquid to solid state is called its freezing point. Different substances have different melting points. However, the freezing point of a substance is the same as its melting point.
• Define latent heat of fusion class 9: "Heat energy required to change unit mass of a substance from solid to liquid state at its melting point without change in its temperature is called its latent heat of fusion".