If two metallic plates of equal thicknesses and thermal conductivities ${K_1}$ and ${K_2}$ are put together face to face and a common plate is constructed, then the equivalent thermal conductivity of this plate will be
  • A$\frac{{{K_1}{K_2}}}{{{K_1} + {K_2}}}$
  • B$\frac{{2{K_1}{K_2}}}{{{K_1} + {K_2}}}$
  • C$\frac{ K _{1}+ K _{2}}{2 K _{1} K _{2}}$
  • D$\frac{ K _{1}+ K _{2}}{ K _{1} K _{2}}$
JEE MAIN 2021, Medium
art

Download our app
and get started for free

Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*

Similar Questions

  • 1
    Liquid cools from $50^oC$  to  $45^oC$  in  $5\  minutes$ and from $45^oC$ to $41.5^oC$ in the next $5\   minutes$.The temperature of the surrounding is ......... $^oC$
    View Solution
  • 2
    The amount of radiation emitted by a perfectly black body is proportional to
    View Solution
  • 3
    $Assertion :$ A hollow metallic closed container maintained at a uniform temperature can act as a source of black body radiation.
    $Reason :$ All metals act as black bodies.
    View Solution
  • 4
    Liquid is filled in a vessel which is kept in a room with temperature ${20^o}C$. When the temperature of the liquid is ${80^o}C$, then it loses heat at the rate of $60\;cal/\sec $. What will be the rate of loss of heat when the temperature of the liquid is ${40^o}C$ ....... $cal/\sec $
    View Solution
  • 5
    A block of metal is heated to a temperature much higher than the room temperature and allowed to cool in a room free from air currents. Which of the following curves correctly represents the rate of cooling
    View Solution
  • 6
    If the temperature of the sun becomes twice its present temperature, then
    View Solution
  • 7
    It is estimated that per minute each $cm^2$ of earth receives about $2\ cal (1\ cal = 4.18\ J)$ of heat  energy from the sun. This is called Solar constant. In $SI$ units the value is
    View Solution
  • 8
    If temperature of $Sun =6000\, K ,$ radius of Sun is $7.2 \times 10^{5}\, Km$ radius of Earth $=6000 \,Km \&$ distance between earth and $Sum =15 \times 10^{7}\, Km .$ Find intensity of light on Earth.
    View Solution
  • 9
    The lengths and radii of two rods made of same material are in the ratios $1 : 2$ and $2 : 3$ respectively. If the temperature difference between the ends for the two rods be the same, then in the steady state, the amount of heat flowing per second through them will be in the ratio
    View Solution
  • 10
    Liquid is filled in a vessel which is kept in a room with temperature ${20^o}C$. When the temperature of the liquid is ${80^o}C$, then it loses heat at the rate of $60\;cal/\sec $. What will be the rate of loss of heat when the temperature of the liquid is ${40^o}C$ ....... $cal/\sec $
    View Solution