Atoms — Physics STD 12 Science — Question

In a sensitive Wheatstone bridge, current in the galvanometer in the state of slight deflection from the position of balance is:

For a transistor, in a common emitter arrangement, the alternating current gain b  is given by

(a) β =

(b) β =

(c) β =

(d) β =

After 1α and 2β emissions

(a) Mass number reduces by 3	(b) Mass number reduces by 4
(c) Mass number reduces by 6	(d) Atomic number remains unchanged

Which of the following statement is correct

(a) Liquids obey fully the ohm's law

(b) Liquids obey partially the ohm's law

(c) There is no relation between current and p.d. for liquids

(d) None of the above

In Young's double slit experiment, 62 fringes are seen in visible region for sodium light of wavelength 5893 Å. If violet light of wavelength 4358 Å is used in place of sodium light, then number of fringes seen will be

(a) 54

(b) 64

(c) 74

(d) 84

Ionization energy of a hydrogen-like ion A is greater than that of another hydrogen-like ion B. Let r, u, E and L represent the radius of the orbit, speed of the electron, energy of the atom and orbital angular momentum of the electron respectively. In ground state:

According to Einstein’s photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal Vs the frequency of the incident radiation gives as straight the whose slope?

A proton (or charged particle) moving with velocity v is acted upon by electric field E and magnetic field B. The proton will move undeflected if

(a) E is perpendicular to B

(b) E is parallel to v and perpendicular to B

(c) E, B and v are mutually perpendicular and

(d) E and B both are parallel to v

Nichrome or Manganin is widely used in wire bound standard resistors because of their: