Related InterviewSolutions

• Current `i` is being driven through a cell of emf `epsilon` and internal resistance3 `r`, as shown (i) the cell absorbs energy at rate of `epsilon i` (ii) The cell stores chemical energy at the rate of `(epsilon i - i^(2)r)` (iii) The potential differnece across the cell is `epsilon+ir` (iv) some heat is produced in the cellA. (i) , (ii)B. (ii), (iii)C. (i),(iii),(iv)D. all
• The production of emf by maintaining a difference of tempreture between the two junctions of two different metals is known asA. Joule effectB. Seebeck effectC. Peltirer effectD. Thomson effect
• In a thermocouple, which of the following statements is not true?A. Neutral temperature depends upon the nature of materials in the thermocoupleB. Temperature of inversion depends upon the tenperature of cold junctionC. When the temperature of the hot junction is equal to the temperature of inversion, the thermo emf becomes zero.D. when the temperature of cold junction increases, the temperature of inversion also increases.
• Thermoelectric constant of a thermocouple are `alpha` and `beta`. Thermoelectric power at inversion tempreture isA. `alpha`B. `- alpha`C. `(alpha)/(beta)`D. `-(alpha)/(beta)`
• The expression for thermo emf in a thermocouple given by the relation `E=40theta-(theta^(2))/(20)`, where `theta` is the temperatue difference of two junctons. For this, the neutral temperature will beA. `100^@C`B. `200^@C`C. `300^@C`D. `400^@C`
• If for a thermocouple `T_(n))` is the neutral temperature, `T_(c )` is the tempreture of the cold junction and `T_(i))` is the temperature of inversion, thenA. `T_i = 2T_(n)-T_(c)`B. `T_i = T_(n)-2T_(c)`C. `T_i = T_(n)-T_(c)`D. None of these
• The cold junction of a thermocouple is maintained at `15^(@)C`. No thermo-emf is developed when the hot junction is mainted at `525^(@)C` . Find neutral temperature.
• A `100W` bulb and a 25W bulb are desigened for the same voltage. They have filaments of the same length and material. The ratio of the diameter of `100W` bulb to that of the `25W` bulb isA. `4:1`B. `2:1`C. `sqrt(2):1`D. `1:2`
• A constant voltage is applied between the two ends of a uniform metallic wire. Some heat is developed in it. The heat developed is doubled ifA. both the length and radius of the wire are halvedB. both the length and radius of the wire are doubledC. the radius of the wire is doubledD. the length of the wire is doubled.
• The walls of a closed cubical box of edge `50cm` are made of a material of thickness `1mm` and thermal conductivity `4xx10^(-4) cm^(-1)(.^@C)^(-1)`. The interior of the box is maintained `100^(@)C` above the outside temperature by a heater placed inside the box and connected across `420V` d.c. calculate the resistance of copper.