Alternating Current — Physics STD 12 Science — Question

What is the ratio of wavelength of radiations emitted when an electron in hydrogen atom jump from fourth orbit to second orbit and from third orbit to second orbit(a) 27 : 25(b) 20 : 27(c) 20 : 25(d) 25 : 27

The explosion of hydrogen bomb is based on the principle of:

The equation E = pc is valid:

All of the following statements are true except(a) Conductance is the reciprocal of resistance and is measured in Siemens(b) Ohm's law is not applicable at very low and very high temperatures(c) Ohm's law is applicable to semiconductors(d) Ohm's law is not applicable to electron tubes, discharge tubes and electrolytes

A capacitor of capacitance 5 micro farads is charged to 1000 volts. The energy stored on the capacitor will be (in joules):

Assertion  : Bohr had to postulate that the electrons in stationary orbits around the nucleus do not radiate.
Reason      : According to classical physics all moving electrons radiate. (a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

An electron beam in an X-ray tube is accelerated through a potential difference of 50000 volts. These are then made to fall on a tungsten target. The shortest wavelength of the X-ray emitted by the tube is(a) 2.5 Å (b) 0.25 nm(c) 0.25 cm(d) 0.025 nm