Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

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

The wavelength of light visible to eye is of the order of:

If the potential at each point on a conductor is same to each other, then:

A particle moves in a closed orbit around the origin, due to a force which is directed towards the origin. The de Broglie wavelength of the particle varies cyclically between two values λ₁, λ₂ with λ₁ > λ₂. Whichof the following statement are true?

In a working nuclear reactor, Cadmium rods, (control rods) are used to

(a) Speed up neutrons	(b) Slow down neutrons
(c) Absorb some neutrons	(d) Absorb all neutrons

an isotope of thorium decays in ten stages emitting six a-particles and four b-particles in all. The end product of the decay is

(a)

(b)

(c)

(d)

Two identical bar magnets are placed on above  the other such that they are mutually perpendicular and bisect each other. The time period of this combination in a horizontal magnetic field is T. The time period of each magnet in the same field is

(a)

(b)

(c)

(d)

Light energy emitted by stars is due to

(a) Breaking of nuclei	(b) Joining of nuclei
(c) Burning of nuclei	(d) Reflection of solar light

The relationship between λ and half life ( of a radioactive substance is

(a) λ =

(b)  λ =

(c) λ =

(d)  λ =

In a semiconductor the separation between conduction band and valence band is of the order of

(a) 100 eV

(b) 10 eV

(c) 1eV

(d) 0 eV