A Tungsten cathode and a thoriated-tungsten cathode have the same geometrical dimensions and are operated at the same temperature. The thoriated-tungsten cathode gives 5000 times more current than the other one. Find the operating temperature. Take relevant data from the previous problem.

The saturation current from a thoriated-tungsten cathode at 2000 K is 100 mA . What will be the saturation current for a pure-tungsten cathode of the same surface area operating at the same temperature? The constant A in the Richardson-Dushman equation is 60 xx 10^4 A m^(-2) K^(-2) for pure tungsten and 3.0 xx 10^(4) A m^(-2) K^(-2) for thoriated tungsten. The work function of pure tungsten is 4.5 eV and that of thoriated tungsten is 2.6 eV .

The saturation current from a thoriated-tungsten cathode at 2000 K is 100 mA . What will be the saturation current for a pure-tungsten cathode of the same surface area operating at the same temperature? The constant A in the Richardson-Dushman equation is 60 xx 10^4 A m^(-2) K^(-2) for pure tungsten and 3.0 xx 10^(4) A m^(-2) K^(-2) for thoriated tungsten. The work function of pure tungsten is 4.5 eV and that of thoriated tungsten is 2.6 eV .

The constant A in the Richardson-Dushman equation for tungsten is 60 xx 10^(4) A m^(-2) . The work function of tungsten is 4.5 eV . A tungsten cathode having a surface area 2.0 xx 10^(-5) m^2 is heated by a 24 W electric heater. In steady state, the heat radiated by the cathode equals the energy input by the heater and the temperature becomes constant. Assuming that the cathode radiates like a blackbody, calculate the saturation current due to thermions. Take Stefan constant = 6 xx 10^(-8) W m^(-2) K^(-4) . Assume that the thermions take only a small fraction of the heat supplied.

The constant A in the Richardson-Dushman equation for tungsten is 60 xx 10^(4) A m^(-2) . The work function of tungsten is 4.5 eV . A tungsten cathode having a surface area 2.0 xx 10^(-5) m^2 is heated by a 24 W electric heater. In steady state, the heat radiated by the cathode equals the energy input by the heater and the temperature becomes constant. Assuming that the cathode radiates like a blackbody, calculate the saturation current due to thermions. Take Stefan constant = 6 xx 10^(-8) W m^(-2) K^(-4) . Assume that the thermions take only a small fraction of the heat supplied.

Consider the situation of the previous problem. Assume that the temperature of the water at the botton of the lake remains contant at 4^(@)C as the ice forms on the surface (the heat required to maintain the temperature of the bottom layer may come from the bed of the lake). The depth of the lake is 1.0m. Show that the thickness of the ice formed attains a steady state mamimum value. Find this value. The thermal conductivity of water =0.50Wm ^(-1) ^(@)C^(-1) . Take other relevent data form the previous problelm.

A L shaped container has dimensions shown in the fig. It has circular cross section of radius R. It is placed on a smooth horizontal table. The container is divided into two equal sections by a membrane AB. One section contains nitrogen and the other one contains oxygen. Temperature of both sides is same but pressure in the compartment having N_(2) is 4 times that in the other compartment. Due to some reason the membrane gets punctured. Find the distance moved by the cylinder if the cylinder is constrained to move in x direction only [with the help of guiding walls W_(1) " and " W_(2) ]. There is no friction anywhere and mass of the cylinder and membrane is negligible

Two electric bulbs have tungsten filament of same length. If one of them gives 60 W and the other 100 W , then

Two electric bulbs have tungsten filament of same length. If one of them gives 60 W and the other 100 W , then