Cathode rays are passing through a discharge tube, in tube, there is
A. an electric field but no magnetic field.

B. a magnetic field but no electric field

C. an electric as well as a magnetic field

D. neither an electric nor a magnetic field

Figure shows two identical triode tubes connected in parallel. The anodes are connected together, the grids are connected together and the cathodes are connected together. Show that the equivalent plate resistance is half to the individual plate resistance. The equivalent mutual conductance is double the individual mutual conductance and the equivalent amplification factor is the same as the individual amplification factor

The plate resistance of a triode is 8 kΩ and the transconductance is 2.5 millimho.

(a) If the plate voltage in increased by 48 V, and the grid voltage is kept constant, what will be the increase in the plate current?

(b) With plate voltage kept constant at this increased value, how much should the grid voltage be decreased in order to bring the plate current back to its initial value?

A triode has mutual conductance = 2.0 millimho and plate resistance = 20 kΩ. It is desired to amplify a signal by a factor of 30. What load resistance should be added in the circuit?

Find the values of r_p, μ and g_m of a triode operating at plate voltage 200 V and grid voltage –6 V. The plate characteristics are shown in figure.

The plate current in a triode can be written as

Show that the mutual conductance is proportional to the cube root of the plate current.

The gain factor of an amplifier is increased from 10 to 12 as the load resistance is changed from 4 kΩ to 8 KΩ. Calculate (a) the amplification factor and (b) the plate resistance.

The plate current, plate voltage and grid voltage of a 6F6 triode tube are related as

I_p = 41(V_p + 7 V_g) ^1.41, Where V_p and V_g are in volts and ip in microamperes. The tube is operated at V_p = 250 V, V_g = –20 V. Calculate

(a) the tube current,

(b) the plate resistance,

(c) the mutual conductance and

(d) the amplification factor.

The plate resistance and the amplification factor of a triode are 10 kΩ and 20. The tube is operated at plate voltage 250 V and grid voltage –7.5 V. The plate current is 10 mA

(a) To what value should the grid voltage be changed so as to increase the plate current to 15 mA?

(b) To what value should the plate voltage be changed to take the plate current back to 10 mA?

The plate current in a diode is 20 mA when the plate voltage is 50 V or 60 V. What will be the current if the plate voltage is 70V?

A triode valve operates at V_p = 225 V and V_g = –0.5 V. The plate current remains unchanged if the plate voltage is increased to 250 V and the grid voltage is decreased to –2.5 V. Calculate the amplification factor.