Concepts Of Physics MCQ Edition [Volume 2]PhysicsElectric Current through Gases

The anode of a thermionic diode is wired to the negative terminal of a battery, while the cathode is wired to the positive terminal.

Options

AA large current will flow through the diode from the cathode to the anode.
BNo appreciable current will flow through the diode.
CThe diode will undergo damage.
DA large current will flow through the diode from the anode to the cathode.

Correct answer

B. No appreciable current will flow through the diode.

Step-by-step solution

In a thermionic diode, the cathode emits electrons when heated. When the anode is connected to the negative terminal of the battery and the cathode to the positive terminal, the diode is reverse-biased. The negative potential of the anode repels the electrons emitted by the cathode, preventing them from reaching the anode. As a result, the circuit remains incomplete and no appreciable current flows through the diode.

Practice Electric Current through Gases on Quantrex Academy →

More from Electric Current through Gases

A pure tungsten cathode and a thoriated-tungsten cathode share the same geometrical dimensions and are operated at a common temperature. The current produced by the thoriated-tungs Determine the ratio n(T)/n(1000 K ) for a tungsten emitter at temperatures T = 300 K , 2000 K , and 3000 K . Here, n(T) denotes the number of thermions emitted per second by the su Within a discharge tube, the mean free path of electrons in the gas is inversely proportional to the internal pressure. The Crookes dark space occupies half the length of the disch At 2000 K , the saturation current from a thoriated-tungsten cathode is 100 mA . Determine the saturation current for a pure-tungsten cathode that has the same surface area and ope Within a discharge tube filled with a gas, a molecule undergoes ionization, causing an electron to be detached. An electric field of 5.0 kV m ⁻¹ is present in the region of the eve Determine the factor by which the emission current changes when the temperature of a tungsten filament is increased from 2000 K to 2010 K . The work function of tungsten is 4.5 eV For tungsten, the constant A in the Richardson–Dushman equation is 60 imes 10^4 A m ⁻² K ⁻² , and its work function is 4.5 eV . An electric heater of 24 W is used to heat a tungste When the plate voltage is 36 V , the power delivered in the plate circuit of a diode is 1.0 W . Determine the power delivered if the plate voltage is raised to 49 V . Assume the La Full Electric Current through Gases list All Concepts Of Physics MCQ Edition [Volume 2] PYQs