The photoelectric threshold wavelength for a metal surface is 6600 Å. The work function for this is
|
(a) 1.87 V |
(b) 1.87 eV |
(c) 18.7 eV |
(d) 0.18 eV |
(b) 1.87 eV
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There is an air filled 1 pF parallel plate capacitor. When the plate separation is doubled and the space is filled with wax, the capacitance increases to 2pF. The dielectric constant of wax is
|
(a) 2 |
(b) 4 |
(c) 6 |
(d) 8 |
The mechanism of the heat produced in a conductor when an electric current flows through it, can be explained on the basis of
|
(a) Viscosity |
(b) Friction |
(c) Free electron theory |
(d) Gauss's theorem |
A coil of N turns and mean cross-sectional area A is rotating with uniform angular velocity w about an axis at right angle to uniform magnetic field B. The induced e.m.f. E in the coil will be
|
(a) NBA sinwt |
(b) NB w sinwt |
(c) NB/A sinwt |
(d) NBA w sinwt |
The energy of electron in the nth orbit of hydrogen atom is expressed as 
. The shortest and longest wavelength of Lyman series will be
| (a) 910 Å, 1213 Å | (b) 5463 Å, 7858 Å | (c) 1315 Å, 1530 Å | (d) None of these |
If cathode rays are projected at right angles to a magnetic field, their trajectory is
|
(a) Ellipse |
(b) Circle |
(c) Parabola |
(d) None of these |