Transfer Of Heat Chapter 9 Physics 9th Class MCQ Test Preparation Federal

Total Questions: 10

Total Marks: 10

Time: 10 Mins

Question # 1

How heat reaches us directly from a fireplace?

Through radiation
Through convection
Through conduction and radiation
Through convection and radiation

Question # 2

Why a glass of chilled water becomes hot after sometime, when the temperature of chilled water glass is lower than the surroundings?

Glass of chilled water conducts less heat than it is absorbing
Glass of chilled water conducts more heat than it is absorbing
Glass of chilled water radiates less heat than it is absorbing
Glass of chilled water radiates more heat than it is absorbing

Heat always passes from a warmer object to a cooler object until all objects are the same temperature.

Question # 3

Why conduction of heat doesn't take place in gases?

None of these
Particles are fixed at their positions
Particles are very near to each other
Particles are far apart from each other

Question # 4

What happens to the thermal conductivity of a wall if its thickness is doubled?

It becomes half
It becomes one fourth
It becomes double
It remains the same

Question # 5

Which of the following statements about copper explains that why it is a better conductor of heat than glass?

There are density changes within the copper
Atomic vibration is passed on to neighboring copper atoms quickly
There are free electrons in the copper
Atoms move through the copper and pass on kinetic energy

Conduction through a material depends on the degree of freedom of the molecules of material.

Question # 6

Which of the following factors effect the rate of transfer of energy in radiation?

Surface temperature
Color and texture of the surface
All of these
Surface area

Radiation is the mode of transfer of heat from one place to another in the form of electromagnetic waves.

Question # 7

2 identical metal plates are painted, one matt (dull) white and the other matt black. These are placed at equal distances from a radiant heater, which is turned on for 5 minutes. Which metal plate absorbs more energy and which plate emits more energy in this time?

White absorbs more and black emits more
Black absorbs and emits more
White absorbs and emits more
Black absorbs more and white emits more

Question # 8

Why are metals good conductors of heat?

Due to presence of free electrons
Due to big size of their molecules
Due to small size of their molecules
Due to rapid vibrations of their atoms

The heat flow mainly depends on the degree of freedom of electrons in a substance.

Question # 9

Why does a metal feel colder to touch than wood when both are kept in a cold place?

Energy transfers rapidly in metal, as it is a thermal conductor
Energy transfers slowly in wood, as it a thermal conductor
Energy transfers rapidly in wood, as it a thermal insulator
Energy transfers slowly in metal, as it is a thermal conductor

Question # 10

How are rooms heated by using gas heaters?

Through conduction only
Through radiation only
Through convection and radiation
Through convection only

Conduction occurs in solids (it is the process of transfer of heat through collisions of body particles,i.e., direct contact), whereas convection occurs in liquids and gases (actual motion of matter)