Tag: heat energy transfers

Quizzes (5) Questions (137)

Questions Related to heat energy transfers

Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

Why is electrical wiring usually covered with a layer of plastic?

  1. To make it look pretty

  2. To help electricity flow along the wire

  3. To make it safe

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Electrical wiring is usually covered with layer of plastic to make it safe. As we know that plastic is an electrical insulator and it is readily available and cheap. So as to insulate the electricity carrying wire, to make it shock free. It is covered with layer of plastic.

Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

A material that does NOT let electricity pass through it is called ...

  1. an electrical conductor

  2. an electrical insulator

  3. an electrical appliance

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A material that does not allow to electricity to pass through, it is called an electrical insulator.
They do not have free electrons present in their outer most shell which would work as charge carriers for conduction of electricity.
Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

Which of these is a good electrical conductor?

  1. Water

  2. Sweat

  3. The human body

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Water is a good electrical conductor but not distilled water. Tap water, Sea water, rain water etc. conduct electricity as they consists of impurities; salts of $Ca, \; Mg,\; Na$ which behave as charge carriers.

Sweat conducts electricity although it is mainly water, it still consists of lot of minerals, lactic acid, urea; in short, it is an ionic liquid (electrolyte)

Human body consists of $75 $% of water and also consists of many minerals and salts. So human body also conducts electricity.
Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

State whether given statement is True or False
In a superconductor, electricity will flow for a long time and then stop.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
False
Superconductors are those materials which have exactly zero resistance and expulsion of magnetic flux occurs when they are cooled below certain temperatures.
Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

State whether given statement is True or False
Innermost electrons are free to move :

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
False
Innermost electrons are not free to move because they are tightly held by the attractive force by the protons present in the nucleus of the element. Only outermost electrons are free to move in conductors.
Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

When electrons in a material are free to move, the material is:

  1. an insulator

  2. a conductor

  3. a semiconductor

  4. none of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
When electrons in a material are free to move, the material is a conductor.
As only conductors have free electrons present in the outermost shell which are mobile and behave as charge carriers and are conduction electrons.
Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

What is NOT an example of an insulator in the kitchen?

  1. An oven mitt

  2. A wooden spoon

  3. Pots and pans

  4. A plastic measuring cup
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pots and pans are NOT example of insulator, they are conductors of heat, if it was not so; they could not be used for cooking of food. And they are used for cooking; so they are conductors.

Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

Which of the following would normally be the best conductor?

  1. Copper

  2. Glass

  3. Steel

  4. Silver
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Among copper, glass, silver and steel, glass is non-metal i.e. insulator; so it has least conductivity.
Conductivity order:
Silver $\gt$ Copper $\gt$ Steel
(in $siemens/m$) at $20^oC$
$62.1\times 10^6 \gt 59.8\times 10^6 \gt 6.21\times 10^6$
Multiple choice physics transfer of heat heat and heat transfer heat energy transfer heat energy transfers fundamentals of heat transfer conduction

Which of these could be used to complete an electrical circuit?

  1. A piece of gravel.

  2. A rubber.

  3. A crayon

  4. Scissors made of iron
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Scissors made of iron could be used to complete an electrical circuit. As iron is a metal and conductor so can conduct electricity easily. And others are non-metals. So they could not conduct electricity and can't complete the circuit.