Nuclei — Physics STD 12 Science — Question

Mark the correct options:

If the two ends of a p-n junction are joined by a wire:

When the velocity of an electron increases, its de Broglie wavelength:

An electron moving with the speed 5   per sec is shooted parallel to the electric field of intensity 1 . Field is responsible for the retardation of motion of electron. Now evaluate the distance travelled by the electron before coming to rest for an instant (mass of e = 9 .  charge = 1.6 )

(a) 7 m

(b) 0.7 mm

(c) 7 cm

(d) 0.7 cm

The velocity of emitted electrons in photelectric effect depends :

A double charged lithium atom is equivalent to hydrogen whose atomic number is 3. The wavelength of required radiation for emitting electron from first to third Bohr orbit in   will be (Ionisation energy of hydrogen atom is 13.6eV)

(a) 182.51 Å

(b) 177.17 Å

(c) 142.25 Å

(d) 113.74 Å

The phase angle between current and voltage in a purely inductive circuit is:

Wave which cannot travel in vacuum is

(a) X-rays

(b) Infrasonic

(c) Ultraviolet

(d) Radiowaves

An inductor, a resistor and a capacitor are joined in series with an AC source. As the frequency of the source is slightly increased from a very low value, the reactance.