The specific charge of a proton is 9.6 x 107 C/kg. The specific charge of an alpha particle will be
9.6 x107 C/kg
19.2 x 107 C/kg
4.8 x107 C/kg
2.4 x 107 C/kg
If λ1 and λ2 are the wavelengths of the first members of the Lyman and Paschen series respectively, then λ1 : λ2 is
1:3
1: 30
7: 50
7: 108
Activity of a radioactive sample decreases to (1/3)rd of its original value in 3 days. Then, in 9 days its activity will become
(1/27) of the original value
(1/9) of the original value
(1/18) of the original value
(1/3) of the original value
If r1 and r2 are the radii of the atomic nuclei of mass numbers 64 and 125 respectively, then the ratio ( r1/ r2 ) is
The principle of LASER action involves
amplification of particular frequency emitted by the system
population inversion
stimulated emission
All of the above
Which of the following is unipolar transistor?
p-n-p transistor
n-p-n transistor
Field effect transistor
Point contact transistor
C.
Field effect transistor
In Field effect Transistor ( FET ) there is only one type of charge for conduction from drain to source i.e either electrons ( n-channel FET ) or holes (P-channel FET).
In NPN and PNP transistor both electron and holes take part in conduction. Hence they are bipolar Junction Transistor.
Point contact Transistor is also Bipolar Junction Transistor.
Light of frequency v falls on material of threshold frequency vo, Maximum kinetic energy of emitted electron is proportional to
ν - νo
ν
vo
A light movs from denser to rarer medium, which of the following is correct?
Energy increases
Frequency increases
Phase changes by 90°
Velocity increases
For a given lens, the magnification was found to be
twice as large as when the object was 0.15 m
distant from it as when the distance was 0.2 m. The
focal length of the lens is
1.5 m
0.20 m
0.10 m
0.05 m