When monochromatic radiation of intensity I falls on a metal surface, the number of photoelectrons and their maximum kinetic energy are N and T respectively. If the intensity of radiation is 2I what is the number of emitted electrons and their maximum kinetic energy?
1. N and 2T
2. 2N and T
3. 2N and 2T
4. N and T
A helium-neon laser produces monochromatic light of a wavelength of 667 nm. The power emitted is 9 mW. The average number of photons arriving per second on average at a target irradiated by this beam is:
A particle of mass 1 mg has the same wavelength as an electron moving with a velocity of .
What will be the velocity of the particle?
(mass of electrons = 9 . 1 × 10- 31 kg )
Waves are associated with matter only:
1. when it is stationary.
2. when it is in motion with the velocity of light only.
3. when it is in motion with any velocity.
4. none of the above.
A particle which has zero rest mass and non-zero energy and momentum must travel with a speed:
1. equal to c, the speed of light in vacuum.
2. greater than c.
3. less than c.
4. tending to infinity.
If the de-Broglie wavelengths for a proton and an alpha-particle are equal, then the ratio of their velocities will be:
1. 4 : 1
2. 2 : 1
3. 1 : 2
4. 1 : 4
How much energy should be added to an electron to reduce its de-Broglie wavelength from m to m?
1. four times the initial energy.
2. thrice the initial energy.
3. equal to the initial energy.
4. twice the initial energy.
If the following particles are moving at the same velocity, then which among them will have the maximum de-Broglie wavelength?
The de-Broglie wavelength of a particle moving with a velocity m/s is equal to the wavelength of the photon.
What is the ratio of the kinetic energy of the particle to the energy of the photon?
(velocity of light is m/s)
A proton and an -particle are accelerated through a potential difference of 100 V.
What is the ratio of the wavelength associated with the proton to that of the alpha-particle?