Electric Charges and Fields — Physics STD 12 Science — Question

The introduction of a grid in a triode valve affects plate current by (a) Making the thermionic emission easier at low temperature(b) Releasing more electrons from the plate(c) By increasing plate voltage(d) By neutralising space charge

The wave theory of light does not explain:

The shortest wavelength of X-rays emitted from an X-ray tube depends on the(a) Current in the tube(b) Voltage applied to the tube(c) Nature of gas in the tube(d) Atomic number of target material

In image formation from spherical mirrors, only paraxial rays are considered because they:

The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use(a) 400 Ω(b) 200 Ω(c) 40 Ω(d) 20 Ω

In a current carrying long solenoid, the field produced does not depend upon(a) Number of turns per unit length(b) Current flowing(c) Radius of the solenoid(d) All of the above three

According to Joule's law, if potential difference across a conductor of material of resistivity remains constant, then heat produced in the conductor is directly proportional to

What is the ratio of the speed of infrared and ultraviolet rays in a vacuum?

What is the average binding energy per nucleon over a wide range?

 What is the full form of UHF?