Electric Charges and Fields — Physics STD 12 Science — Question

Two charged spheres of radii 10 cm and 15 cm are connected by a thin wire. No current will flow, if they have(a) The same charge on each(b) The same potential(c) The same energy(d) The same field on their surfaces

Assertion  : In high latitude one sees colourful curtains of light hanging down from high altitudes.
Reason      :  The high energy charged particles from the sun are deflected to polar regions by the magnetic field of the earth.(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.

Magnetic lines of force:

Assertion :   At 0 K Germanium is a superconductor. 
Reason    :    At 0 K Germanium offers zero resistance.(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.

Hydrogen atom emits blue light when it changes from n = 4 energy level to the n = 2 level. Which colour of light would the atom emit when it changes from the n = 5 level to the n = 2 level(a) Red(b) Yellow(c) Green   (d) Violet

S.I. unit of self-induction is :

The ratio of the kinetic energy to the total energy of an electron in a Bohr orbit is(a) – 1(b) 2(c) 1 : 2(d) None of these

All particles of a wave front vibrate:

Two lithium nuclei in lithium vapour at room temperature do not combine to form a carbon nucleus because: