The ratio of the dimensions of Planck's constant and that of the moment of inertia is the dimension of
frequency
velocity
angular momentum
time
A photosensitive metallic surface has work function, h vo, If photons of energy 2hvo, fall on this surface, the electrons come out with a maximum velocity of 4 x 106 m/s. When the photon energy is increased to 5 hv,, then maximum velocity of photoelectrons will be
2 × 106 m/s
2 × 107 m/s
8 × 105 m/s
8 × 106 m/s
D.
8 × 106 m/s
The solution to our problem consists in Einstein's photoelectric equation.
Einstein's photoelectric equation can be written as
Dividing equation (ii) by eq (i)
The efficiency of photoelectric effect is less than 1 o .ie, number of photons less than 1 % are capable of ejecting photoelectrons.
Fission of nuclei is possible because the binding energy per nucleon in them
increases with mass number at high mass numbers
decreases with mass number at high mass numbers
increases with mass number at low mass numbers
decreases with mass number at low mass numbers
In any fission process the ratio is
less than 1
greater than 1
greater than 1
depends on the mass of parent nucleus
Zener diode is used for
producing oscillations in an oscillator
amplification
stabilisation
rectification
The angular resolution of a 10 cm diameter telescope at a wavelength of 5000 A is of the order of
106 rad
10-2 rad
10-4 rad
10-6 rad
Carbon, silicon and germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by respectively. Which one of the following relationships is true in their case?
Choose the only false statement from the following
Substances with energy gap ofthe order of 10 eV are insulators
The conductivity of a semiconductor increases with increases in temperature
In conductors the valence and conduction bands may overlap
The resistivity of a semiconductor increases with increase in temperature
Copper has face-centred cubic ( FCC ) lattice with interatomic spacing equal to 2.54 A. The value of lattice constant for this lattice is
1.27 Ao
5.08 Ao
2.54 Ao
3.59 Ao
The total energy of an electron in the first excited state of hydrogen is about -3.4 eV. Its kinetic energy in this state is
-3.4 eV
-6.8 eV
6.8 eV
3.4 eV