Why is the cathode ray tube evacuated to a low pressure?
To avoid the effect of external electric field on the beam of electrons.
To increase the energy of the beam of electrons.
To avoid collisions of electrons with the air molecules
To increase the rate of emission.
Which of the following metals cannot be used to coat tungsten inorder to reduce its work function?
Magnesium
Strontium
Cesium
Barium
Speed of beta particle is
107 m/s
2.7 x 108 m/s
3 x 108 m/s
108 m/s
Who discovered radioactivity?
Albert Einstein
Ernest Rutherford
Antoine Henri Becquerel
James Chadwick
A certain nucleus A (mass number 238 and atomic number 92) is radioactive and becomes a nucleus B (mass number 234 and atomic number 90) by the loss of a particle. What particle was emitted?
Gamma
neutrino
alpha
beta
A certain nucleus X has a mass number 15 and atomic number 7.Find the number of neutrons.
15
7
8
22
On increasing the filament current:
rate of emission of electrons increase
electron beam gets deflected strongly
brightness pattern on the screen changes
energy of emitted electrons increase
Choose the work function of Platinum.
6.2
4.52
4.37
2.6
A T V tube requires an accelerating voltage of the order of
150 V
1000 V
20 kV
500 kV
Which of the following is an Isotop of ?