MCQ
The photoelectric effect proves that light consists of :
- APhotons
- BElectrons
- CElectromagnetic waves
- DMechanical waves
Explanation:
It's been determined experimentally that when light shines on a metal surface, the surface emits electrons. For example, you can start a current in a circuit just by shining a light on a metal plate. we were saying earlier that light is made up of electromagnetic waves, and that the waves carry energy. So if a wave of light hit an electron in one of the atoms in the metal, it might transfer enough energy to knock the electron out of its atom. Light has sometimes been viewed as a particle (photon) rather than a wave. If it's waves, the energy contained in one of those waves should depend only on its amplitude--that is, on the intensity of the light.
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Through which mode of propagation, the radio waves can be sent from one place to another
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(a) Ground wave propagation |
(b) Sky wave propagation |
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(c) Space wave propagation |
(d) All of them |
An electric dipole is placed in an electric field generated by a point charge
|
(a) The net electric force on the dipole must be zero |
|
(b) The net electric force on the dipole may be zero |
|
(c) The torque on the dipole due to the field must be zero |
|
(d) The torque on the dipole due to the field may be zero |
In P-type semiconductor, there is
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(a) An excess of one electron |
(b) Absence of one electron |
|
(c) A missing atom |
(d) A donar level |
The work function for metals A, B and C are respectively 1.92 eV, 2.0 eV and 5 eV. According to Einstein’s equation, the metals which will emit photo electrons for a radiation of wavelength 4100 Å is/are
|
(a) None of these |
(b) A only |
(c) A and B only |
(d) All the three metals |