A potentiometer wire is 100 cm long and a constant potential difference is maintained across it. Two cells are connected in series first to support one another and then in opposite direction. The balance points are obtained at 50 cm and 10 cm from the positive end of the wire in the two cases. The ratio of the emf's is :
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Suppose voltage V is applied across a resistance R. The power dissipated in the resistance is P. Now the same voltage V is applied across a parallel combination of three equal resistors each of resistance R. Then the power dissipated in the second case will be
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A galvanometer can be converted into a voltmeter by connecting with it a
A. High resistance in parallel
B. Low resistance on parallel
C. High resistance on series
D. Low resistance in series
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In superconductors, the energy gap is due to
A. Electron-electron interaction
B. Electron-phonon interaction
C. Phonon-phonon interaction
D. Electron-photon intercation
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Electrical Pressure is also called
A. Current
B. Voltage
C. Resistance
D. Power
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The ''Choke' used with a tube light is basically
A. An inductor
B. A capacitor
C. A transformer
D. A resistor
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For photoelectric effect to take place, the metal used as the cathode should have ________
A. High melting point
B. Low melting point
C. Low work function
D. Low resistance
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Which phenomena shows the particle nature of light?
A. Diffraction
B. Interference
C. Photoelectric effect
D. Polarisation
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According to the quantum theory of light, the energy of light is carried in discrete units are called
A. Photoelectrons
B. Protons
C. Electrons
D. Photons
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Photon is the fundamental unit/quantum of
A. Gravitation
B. Electricity
C. Magnetism
D. Light
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The energy of a photon, whose momentum is 10 MeV/c, where c is the speed of light, is given by
A. 10 MeV
B. 100 MeV
C. 1 MeV
D. 0.1 MeV
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The energy of a photon varies directly with its
A. Wave length
B. Frequency
C. Speed
D. None of the above
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A photon of X-ray has energy of 1 keV. A photon of visible radiation has energy of 3 eV. In this context, which one of the following statements is not correct?
A. The wavelength of X-ray photon is less than the wavelength of visible radiation photon.
B. Both the photons have different energies.
C. The speeds of both the photons in vacuum are different
D. The frequency of X-ray photon is higher than the frequency of visible radiation photon.
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The threshold frequency is the frequency below which :
A. Photo current increases with voltage
B. Photo current decreases with voltage
C. Photo electric emission is not possible
D. Photo current is constant
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Which of the following supports particle nature of photons ?
A. Diffraction
B. Polarization
C. Photoelectric effect
D. Interference
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The reverse effect of X–ray emission is
A. Raman effect
B. Compton effect
C. Zeeman effect
D. Photoelectric
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The term photon refers to
A. Light ray
B. Sub atomic particle
C. Radiation
D. None of the above
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In a conductor
A. There is no conduction band
B. The forbidden energy gap is very wide
C. The forbidden energy gap is very narrow
D. The valence band and the conduction band overlap each other
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The unit of intensity of electric field is
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. . . . . . . . . exerts a force on anything that has an electric charge.
A. Electric field
B. Electrostatic force
C. Inductive field
D. All of the above
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