The cathode of a diode valve is replaced by another cathode of double the surface area. Keeping the voltage and temperature conditions the same, will the plate current decrease, increase or remain the same?

A parallel -plate capacitor is connected to a battery that maintains a constant potential difference V between the plates. If the plates are pulled away from each other, increasing their separation, does the magnitude of the charge on the plates (a) increase, (b) decrease, or (c ) remain the same ?

The figure here shows four rectangular metal plates, with sides of , L , 2L or 3L. They are all made of the same material , and their temperature is to be increased by the same amount , Rank the plates according to the expected increase in (a) their vertical heights and (b) their areas , greatest first.

A charged isolated metal sphere of diameter 15cm has a potential of 6500V relative to V=0 at infinity. (a) calculate the energy density in the electric field near the surface of the sphere. (b) IF the diameter is decreased, does the energy density near the surface increase, decrease or remain the same?

If the altitude of a triangle is increased by 10% while its area remains the same, its corresponding base will have to be decreased by

A solenoid carrying a current supplied by a DC source with a constant emf contains an iron core inside it. How will the current change when the core is pulled out of the solenoid: will it increase, decrease, or remain the same?

The constant A in the Richardson-Dushman equation for tungsten is 60 xx 10^(4) A m^(-2) . The work function of tungsten is 4.5 eV . A tungsten cathode having a surface area 2.0 xx 10^(-5) m^2 is heated by a 24 W electric heater. In steady state, the heat radiated by the cathode 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 xx 10^(-8) W m^(-2) K^(-4) . Assume that the thermions take only a small fraction of the heat supplied.

If the altitude of a triangle is increased by 10% while its area remains same, its corresponding base will have to be decreased by

The capacitance of a parallel plate capacitor when a very thin metallic sheet is placed in the space between the plates, parallel to the plates , will (1) Increase (2) Decreases (3) Remain same (4) Nothing can be said

Two plates of equal areas are placed in contact wih each other. Their thickness are 2.0 cm and 5.0 cm respectively. The temperature of the external surface of the first plate is -20^(@)C and that of the external surface of the second plate is 20^(@)C . What will be the temperature of the current surface if the plates (i) are of the same material, (ii) have thermal conductivities in the ratio 2:5 .