Tag: heat energy transfers

Quizzes (5) Questions (137)

Questions Related to heat energy transfers

Multiple choice physics heat energy transfers heat energy heat, internal energy and work internal energy

According to law of conservation of energy, heat energy is transformed into which two types of energy?

  1. Kinetic and potential energy

  2. Mechanical and potential energy

  3. Kinetic and thermal energy

  4. Nuclear and potential energy
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to law of conservation of energy, heat energy is transformed into Kinetic and potential energy

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

A geyser heats water flowing at the rate of 4 litre per minutes from 30 C to 85 C. If the geyser operates on gas burner then the amount of heat used per minute is :

  1. $9.24\times { 10 }^{ 5 }$J

  2. $6.24\times { 10 }^{ 7 }$J

  3. $9.24\times { 10 }^{ 7 }$J

  4. $6.24\times { 10 }^{ 5 }$J
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For one minute

$H=mC\theta$
$=4kg\times 4200\times55\=924000J\=9.24\times 10^5j$

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

A 2 m long wire of resistance 4 ohm and diameter 0.64 mm is coated with plastic insulation of thickness 0.06 mm, when a current of 5 ampere flows through the wire, find the temperature difference across the insulation in steady state if $k=0.16\times { 10 }^{ -2 }cal/\left( cm{ C }^{ 0 }sec \right) $ 

  1. ${ 3 }^{ \circ }C$

  2. ${ 2 }^{ \circ }C$

  3. ${ 4 }^{ \circ }C$

  4. ${ 1 }^{ \circ }C$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The temperature difference across cylindrical insulation is given by ΔT = Q × ln(r2/r1) / (2πkL), where Q = I²R. For the given values (wire radius 0.32mm, insulation thickness 0.06mm, k=0.16×10⁻², L=200cm, Q=5²×4=100W), the temperature difference works out to approximately 3°C. The insulation thickness is small compared to wire radius, which affects the logarithmic term in the heat transfer equation.

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

Name a medium which is a good insulator of heat.

  1. Still (or trapped) air

  2. Oil

  3. Steam

  4. solid copper
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Trapped(still) air is good insulator.
Thermal conductivity of air is small as compared to solid and liquid. Eg- glass conducts 30 times more power per unit distance per unit temperature than air.
The less dense the material, the less thermal conductivity. And gas(air) is least dense than solid and liquid.
Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

A cotton sheet is ironed with hot electricity. How is energy transferred through the metal base of the iron to the sheet?

  1. by conduction only

  2. by convection only

  3. by radiation only

  4. by convection and radiation only
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Conduction occurs when two objects at different temperatures are in contact with each other. Heat flows from the warmer to the cooler object until they are both at the same temperature.
The iron and cotton sheet is in contact with each other so, there is conduction between them.

Energy transformation while ironing clothes takes out their wrinkles and makes them smooth. This takes the heat, which is one type of energy. In the iron, electrical energy is used, and it is transformed into heat energy.

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

Two layers of cloth of equal thickness provide warmer covering than a single layer of cloth of double the thickness, because they :

  1. behave like a thermos

  2. have lesser thickness

  3. allow heat from atmosphere to the body

  4. enclose between them a layer of air
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Air is a bad conductor of heat, hence if layer of air is isolated between two layers of cloth, warmer covering will be provided than if only one layer of cloth, where only body is isolated from surrounding air by cloth. 

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

Mercury is generally used in thermometer because it has a

  1. High fluidity

  2. High density

  3. High coefficient of expansion

  4. High specific heat
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Most metals are good conductors of heat and they are solids at room temperature. 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.