Tag: conduction

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Multiple choice physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

At a common temperature ,a block of wood and a block of metal feel equally cool or hot. The temperatures of metal and wood are

  1. $Less$ $than$ $the$ $temperature$ $of$ $the$ $body$

  2. $Equal$ $than$ $the$ $temperature$ $of$ $the$ $body$

  3. $Greater$ $than$ $the$ $temperature$ $of$ $the$ $body$

  4. $Either$ $(a)$ $or$ $(c)$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When objects are at the same temperature as the surroundings, they feel different because of their thermal conductivity. Metal conducts heat away from the hand faster than wood, making it feel colder, even though they are at the same temperature.

Multiple choice physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

Choose the correct experiment to demonstrate the transfer of heat by the process of conduction.

  1. <span>Take two metal blocks of same size &amp; shape and heat one of them to a considerable temperature, then allow both the blocks to touch each other, after a while, you will see the other block gets heated due to contact.</span>

  2. <span>Take two metal blocks of same size &amp; shape and heat one of them to a considerable temperature, then keep the blocks separate, after a while you will see the other block gets heated due to contact.</span>

  3. <span>Take two metal blocks of same size &amp; shape and heat one of them to a considerable temperature, then allow both the blocks to touch each other after the block get cooled down, after a while you will see the other block gets heated due to contact.</span>

  4. None of above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Take two metal blocks of same size & shape and heat one of them to a considerable temperature, then allow both the blocks to touch each other, after a while you will see the other block gets heated due to contact.

Multiple choice physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

If a rod is in a variable state (not in steady state), then

  1. Temperature gradient remains constant

  2. Temperature of rod is function of time and distance from one of end

  3. Temperature of rod is only function of distance from one of end

  4. Temperature of rod is only function of time
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a variable state (non-steady state), the temperature at any point in the rod changes with time as heat is absorbed by the material to change its internal energy. Therefore, temperature is a function of both position and time.

Multiple choice physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

State true or false:
The more is the temperature difference of hot and cold body more slowly the heat flows from it into the cold body

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The amount of heat leaving the hot object will be equal to the amount of heat received by the colder object (assuming nothing else is around to receive some of the heat). The rate at which heat transfers from the hotter object to the colder object increases with the temperature difference between the objects.
Multiple choice physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

By which of the following methods could a cup of hot tea lose heat when placed on metallic table in a class room
a) conduction
b) convection
c) radiation
d) evaporation of liquid.

  1. a, b

  2. b,c

  3. a,b,c

  4. a,b,c,d
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Conduction occurs through the walls of the cup.
Radiation occurs from the top surface.
Convection occurs at the top of the cup.
Evaporation of liquid also occurs.

Multiple choice physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

The quantity of heat flowing for $10 \ s$ through a rod of length $40\ cm$, area $50 \ cm^{2}$ is $200\ J$. If the temperature difference at the ends of the rod is 80$^{o}$C , the coefficient of thermal conductivity of the rod in Wm$^{-1}$K$^{-1}$ is:

  1. $20$

  2. $60$

  3. $80$

  4. $120$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$Q = 200$
$A = 50 \times 10^{-4}\ m^2$
${\theta}^{} _{1} = 80^\circ C    ;   \ \ {\theta}^{} _{2} = 0$
$t = 10\ s ; \ \    l  = 0.40\ m$
$Q = \dfrac{KA\Delta T t}{L}$
$200 = \dfrac{K  \times 50\times 10^{-4}\times    80\times    10}{0.4}$ 
$K = 20\ W/mK$ 

Multiple choice physics temperature and heat modes of heat transfer - conduction conduction heat and modes of heat transfer

A red hot brick is placed on an iron tripod stand which stands on a large block of copper. The brick loses heat by:

  1. conduction

  2. conduction and radiation

  3. conduction and convection

  4. conduction, convection, and radiation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The brick loses heat (i) by conduction through iron tripod stand to the copper block which is then radiated away and convection currents are set up in the surrounding air, and (ii) by radiation.