0
question_answer1) Heat is flowing through the cylindrical rods of the same material. The diameters of the rods are in the ratio 1:2 and their lengths are in the ratio 2:1. If the temperature difference between their ends is the same then the ratio of the amount of heat conducted through them per unit time will be-
question_answer2) A slab consist of two parallel layers of copper and brass of the same thickness and having thermal conductivities in the ratio 1:4. If the free face of brass is at \[100{}^\circ C\] and that of copper at \[0{}^\circ C\], find the temperature of interface (in \[{}^\circ C\])
question_answer3) Two identical square rods of metal are welded end to end as shown in figure (a). 20 calories of heat flows through it in 4 minutes. If the rods are welded as shown in figure (b). The same amount of heat will flow through the rods in (in min)
question_answer4) A wall has two layers A and B, each made of different materials. Both the layers have the same thickness. The thermal conductivity of the material of A is twice that of B. Under thermal equilibrium, the temperature difference across the wall is\[36{}^\circ C\]. Find the temperature difference across the layer A (in \[{}^\circ C\])
question_answer5) Three rods made of the same material and having the same cross-section have been joined as shown in the figure. Each is of the same length. The left and right ends are kept at \[0{}^\circ C\]and \[90{}^\circ C\]respectively. The temperature of the junction of the three rods will be (in \[{}^\circ C\])?
question_answer6) Two rectangular blocks A and B of different metals have same length and same area of cross-section. They are kept in such a way that their cross-sectional area touches each other. The temperature at one end of A is \[100{}^\circ C\]and that of B at the other end is\[0{}^\circ C\]. If the ratio of their thermal conductivity is 1:3, then under steady state, the temperature of the junction in contact will be (in \[{}^\circ C\])?
question_answer7) A thin square steel plate with each side equal to 10 cms is heated by a blacksmith. The rate of radiated energy by the heated plate is 1134 watts. The temperature of the hot steel plate is (in K)- (Stefan's constant \[\sigma =5.67\times {{10}^{-8}}\]watts \[{{m}^{-2}}{{K}^{-4}}\]emissivity of the plate\[=1\])
question_answer8) The rate of emission of radiation of a body at temperature \[27{}^\circ C\]is 20 watt. If the temperature of a body is increased to \[327{}^\circ C\], the rate of emission of radiation(in Watt) will be ?
question_answer9) The coefficient of thermal conductivity of copper is nine time that of steel. In the composite cylindrical bar shown in Fig. What will be the temp. at the junction of copper and steel?(in \[{}^\circ C\])
question_answer10) Two metal cubes A and B of same size are arranged as shown in fig. The extreme ends of the combination are maintained at \[100{}^\circ C\]and \[0{}^\circ C\]as shown. The arrangement is thermally insulated. The coefficients of thermal conductivities of A and B are 300 W/m-\[{}^\circ C\]and 200 W/m-\[{}^\circ C\] respectively. After steady state is reached, the temperature of the interface will be(in \[{}^\circ C\])
question_answer11) Two spheres of the same material have radii 1m and 4m and temperatures 4000 K and 2000 K respectively. The ratio of the energy radiated per second by the first sphere to that by the second is
question_answer12) A steel frame\[(K=45\text{ }W/m{}^\circ C)\] total length 60 cm and cross-sectional area 0.20 \[c{{m}^{2}}\] forms three sides of squire. The free ends are maintained at \[20{}^\circ C\] and \[40{}^\circ C\]Find the rate of heat flow through a cross-section of the frame. (in Watt)
question_answer13) The temperature of a room is maintained uniform through out the room at \[15{}^\circ C\] by a heater of resistance 25 ohms connected to 220 volts mains. Calculate the temperature outside if heat transmitted through a glass window of thickness 0.4 cm, and area 1 square. Metre [\[K\text{ }for\text{ }glass=0.002\]\[\frac{cal}{cm.\sec .{}^\circ C}\]units and\[J=4.2\text{ }joule/cal\]]
question_answer14) Two slabs A and B of conductivities 126 and 168 SI units respectively and of same area and same thickness are placed in contact along their surfaces. The temperature of the outward surfaces of A and B are respectively \[100{}^\circ C\]&\[30{}^\circ C\]. Calculate the temperature of the surface in contact. (in \[{}^\circ C\])
question_answer15) Two rods shown in figure have identical geometrical dimensions. They are in contact with two heat baths at temperature \[100{}^\circ C\] and\[0{}^\circ C\]. The temperature of the junction is\[70{}^\circ C\]. Find the temperature of the junction if the rods are interchanged. (in \[{}^\circ C\])
Please Wait you are being redirected....
You need to login to perform this action.You will be redirected in 3 sec
OTP has been sent to your mobile number and is valid for one hour
Your mobile number is verified.
