Critical Frequency (Ionosphere) (f_c = 9√(N_max))
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f_c = 9√(N_max)
What each symbol means
| Symbol | What it stands for |
|---|---|
| f_c | Critical frequency of an ionospheric layer (MHz) in the usual JEE shortcut form |
| N_max | Maximum electron number density in that layer, expressed in the problem's agreed unit block (often N_max/(10¹¹ m⁻³) so that 9√N gives MHz — match the question's data statement) |
When to use this
Standard Indian textbook / JEE shortcut relating plasma cutoff to electron density; always use the unit convention printed with the numerical data.