Q. 9

# The constant A in the Richardson-Dushman equation of tungsten is 60 × 104 A m-2 K-2. The work function surface area 2.0 × 10–5 m2 is heated by a 24 W electric 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 × 10-8 W m-2 K-4. Assume that the thermions take only a small fraction of the heat supplied.

Given

A=60 × 104 A m-2 K-2

S=2.0 × 10–5 m2

P=24 W =6 × 10-8 W m-2 K-4

The power radiated by Stefen’s law is given by    According to Richardson-Dushman Equation thermionic current i is where, n is the thermions emitted, S is the surface area, T is the absolute temperature, k is the Boltzmann constant, A is the constant depend on nature of metal and ϕ is the work function   Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos  Electric Dipole46 mins  Electric field inside cavity37 mins  Electric Flux - Theory46 mins  Test Your Knowledge of Electric Charge & Coulomb's Law47 mins  Check your knowledge of Electric Potential | Quiz45 mins  Electric Charges and Fields - 0556 mins  Relation between electric field and potential34 mins  Few Applications of Gauss's law54 mins  10 Problems on related to Electric Field & Charges41 mins  Electric Charges and Fields - 0352 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation view all courses 