The direction of flow of heat is
Heat transfers from hotter objects to cooler object. That happens because the molecules hit each other, and the faster moving molecules in the hot object spread that energy into the cooler object.
Which of the following devices is used for measurement of temperature of human body?
To X measure temperature of human body we use clinical thermometer or doctor's thermometer.
The clinical thermometers presently in use in India are marked with a temperature scale. This scale corresponds to which of the following?
The scale presently used in India for clinical thermometer is Celsius scale.
The normal temperature of human body is
Normal temperature of human body is
The flow of heat by conduction is generally observed in case of
In solids heat flows from one part of the solid to another part by conduction.
In which mode of heat transfer does the transfer of heat occur as a wave?
In radiation heat is transferred as a wave.
One feels sensation of heat when exposed to
Infrared rays are also known as heat waves. Greenhouse gases reflect the heat in the form of infra red rays . So, infrared rays are very important to global warming.
Which of the following is a good conductor of heat?
Aluminum is a good conductor of heat.
In sea breeze
Sea breezes occur during hot, summer days because of the unequal heating rates of land and water. During the day, the land surface heats up faster than the water surface. Therefore, the air above the land is warmer than the air above the ocean. As a result, cold air moves from sea towards land during day Time.
In land breeze
cold air moves from land towards sea during night.
Mercury is generally used in thermometer because it has a
Mercury is the only one in liquid state at room temperature. It's used in thermometers because it has high coefficient of expansion. Hence, the slightest change in temperature is notable when it's used in a thermometer.
Nights are cooler in the deserts because
sand radiates heat more quickly as compared to earth
Seema is in a hurry and wants her noodles to cool down faster. She should put it on a plate made of
A metal plate due to its better thermal conductivity, draws heat faster from our hand than a plastic plate. This makes us feel that the steel plate is colder than the plastic one.
On a Fahrenheit scale
On a Fahrenheit scale:
(i) Boiling point of water is 212∘F.
(ii) The temperature will be equal to that on the Celsius scale at −40∘C.
(iii) The difference between the upper fixed point and the lower fixed point is divided into 180 equal parts.
Expansion of a substance on heating depends on
Thermal expansion is the change in size of an object as its temperature changes, Normally as the temperature increases, the size of an object also increases. Hence expansion of a substance on heating depends on nature of substance and rise in temperature.
On a cold day, it is hard to open the lid of a tight container. But when you gently heat the neck you can easily open the lid. Why?
Lid expands more than the neck and thus slides easily
Process of change of state from gaseous state to liquid state is called
Condensation is the process by which water vapor in the air is changed into liquid water.
When two bodies at different temperatures are placed in thermal contact with each other, heat flows from the body at higher temperature to the body at lower temperature until them both acquire the same temperature. Assuming that there is no loss of heat to the surroundings, the heat
the heat lost by the hotter body will be equal to the heat gained by the colder body.
We receive heat energy from the sun through ______ mode of transmission
Since there is no medium between sun and earth heat can travel only through radiation.
Conduction is possible
bodies should be in contact and should have different temperatures