Magnetism And Matter — Physics STD 12 Science — Question

The triode constant is out of the following

(a) Plate resistance

(b) Amplification factor

(c) Mutual conductance

(d) All the above

A ball kept in a closed box moves in the box making collisions with the walls. The box is kept on a smooth surface. The velocity of the centre of mass:

1. Of the box remains constant.
2. Of the box plus the ball system remains constant.
3. Of the ball remains constant.
4. Of the ball relative to the box remains constant.

Two electrons in an atom are moving in orbit of radii R and 9R respectively. The ratio of their frequencies will be:

A radioactive nucleus  decays to  . Which of the following particles are emitted

(a) One alpha and one electron	(b) Two deuterons and one positron
(c) One alpha and one proton	(d) One proton and four neutrons

A beam of well collimated cathode rays travelling with a speed of 5   enter a region of mutually perpendicular electric and magnetic fields and emerge undeviated from this region. If |B| = 0.02T, the magnitude of the electric field is

(a)

(b) 2.5

(c) 1.25

(d) 2

Let n_p and n_e be the number of holes and conduction electrons in an intrinsic semiconductor.

If the field lines in a magnetic field are parallel and equidistant, the magnetic field is __________ .

If Young's double slit experiment is performed in water:

A  cut diamond sparkles because of its

(a) Hardness	(b) High refractive index
(c) Emission of light by the diamond	(d) Absorption of light by the diamond

Atom bomb consists of two pieces of   and a source of

(a) Proton

(b) Neutron

(c) Meson

(d) Electron