Light of wavelength 5000 is incident normally on a slit of width 2.5 x 10-4 cm. The angular position of second minimum from the central maximum is
An electron of mass me and a proton of mass mp are accelerated through the same potential. Then, the ratio of their de-Broglie wavelengths is
1
The half-life of a radioactive substance is 20 min. The time taken between 50 % decay and 87.5 % decay of the substance will be
20 min
30 min
40 min
25 min
If the frequency of incident light falling on a photosensitive metal is doubled, the kinetic energy of the emitted photoelectron is
unchanged
halved
doubled
more than twice its initial value
The significant result deduced from the Rutherford's scattering experiment is that
whole of the positive charge is concentrated at the centre of atom
there are neutrons inside the nucleus
α-particles are helium nuclei
electrons are embedded in the atom
On an average, the number of neutrons and the energy of a neutron released per fission of a uranium atom are respectively
2.5 and 2 keV
3 and 1 keV
2.5 and 2 MeV
2 and 2 keV
The inputs A, B and C to be given in order to get an output Y = 1 from the following circuit are
0, 1, 0
1, 0, 0
1, 0, 1
1, 1, 0
The collector resistance and the input resistance of a CE amplifier are respectively 10 kΩ and 2 kΩ. If β of the transistor is 49, the voltage gain of the amplifier is
125
150
245
200
The light emitting diode (LED) is
a heavily doped p-n junction with no external bias
a heavily doped p-n junction with reverse bias
a heavily doped p-n junction with forward bias
a lightly doped p-n junction with no external bias
C.
a heavily doped p-n junction with forward bias
The light emitting diode (LED) is a heavily doped p-n junction with forward bias. Because it is an important light source used in optical communication and is based on the principle of conversion of biasing electricity into light. It is a specially designed forward-biased p-n junction diode which emits light spontaneously when energised.