Doubly ionised helium atoms and hydrogen ions are accelerated from rest through the same potential dop. The ratio of the final velocities of the helium and the hydrogen ion is
2
Which of the following is true ?
The stopping potential increases with increasing intensity of incident light
The photocurrent increases with increasing intensity of light
The current in photocell increases with increasing frequency of light
The photocurrent is proportional to applied voltage
When light of wavelength 300nm (nanometer) falls on a photoelectric emitter, photoelectrons are liberated. For another emitter, however, light of 600 nm wavelength is sufficient for creating photoemission, what is the ratio of the work functions of the two emitters ?
1 : 2
2 : 1
4 : 1
1 : 4
Which of the following are thermions ?
Protons
Electrons
Photons
Positrons
J J Thomson's cathode ray tube experiment demonstrated that
the e/m of electrons is greater than the e/m of protons
the e/m ratio of the cathode ray particles changes when a different gas is placed in the discharge tube
cathode rays are streams of negatively charged ions
all the mass of an atom is essentially in the nucleus
A light source is at a distance d from a photoelectric cell, then the number of photoelectrons emitted from the cell is n. If the distance of light source and cell is reduced to half, then the number of photoelectrons emitted will become
2n
4 n
n
In X-rays diffraction experiment distance between atomic lattice planes of diffraction grating is 2.8 ×10-10 m, then the maximum wavelength of X-rays (in metre) is
2.5
5.6 × 10-10
4 × 10-10
4.6 × 10-10
Light of wavelength 5000Å falls on a sensitive plate with photoelectric work function of 1.9 eV. The kinetic energy of the photoelectron emitted will be
0.58 eV
2.48 eV
1.24 eV
1.16 eV
The nature of ions knocked out from hot surfaces is
protons
electrons
neutrons
nuclei
The 21 cm radiowave emitted by hydrogen in interstellar space is due to the interaction called the hyperfine interaction in atomic hydrogen. The energy of the emitted wave is nearly
10-17 J
1 J
7 × 10-6 J
10-24 J
