Give reasons for the following.
a- When we touch a steel rod and a paper sheet simultaneously, we find that the rod is cooler than the paper sheet.
b- Mercury is widely used in clinical thermometers.
c- The handles of cooking vessels are generally made up of or covered with plastic or wood.
Answers
Answer:
Paper is a bad conductor of heat/cold whereas steel is a good conductor of heat/cold. So it is cooler to touch
Mercury does not stick to the sides of the thermometer, so giving accurate measurements. That's why it is used in thermometer.
Plastic or wood are a bad conductor of heat, so it prevents burning of hands. It also doesn't melt easily (in case of plastics). So, it is used as handles of cooking vessels
a- We find that the rod is cooler than the paper sheet because the molecules of rod are tightly packed while paper sheet's molecules are not tightly packed.
b- Mercury has the hight coefficient of expansion. That's why it is widely used in clinical thermometers.
c- Because plastic and wood materials are bad conductors of heat and they cannot allow heat of the flame to the person's hand.