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QPage 352: Q4: HC Verma: Concepts of Physics - Volume 2 Electric Current through Gases Page 352: Q4 Solution: The saturation current in a triode valve can be changed by…

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Saturation current in a triode is the thermionic‑emission current from the cathode, determined by its temperature ($I_spropto e^{-W/kT}$). It is independent of grid or plate voltages (until space‑charge limits). Do not assume that changing $V_g$ or $V_p$ will alter the saturation current.

The saturation current in a triode valve can be changed by changing ___________ .

Multiple Choice Options

  • A the grid voltage
  • B the plate voltage
  • C the separation between the grid and the cathode
  • D the temperature of the cathode

Step-by-Step Verified Solution

**Answer:** (d) the temperature of the cathode. **Step-by-Step Explanation:** Saturation current depends on the rate of thermionic emission, which depends on cathode temperature.

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