Force between two identical bar magnets whose centres are r metre apart is 4.8 N, when their axes are in the same line. If separation is increased to 2r, the force between them is reduced to
|
(a) 2.4N |
(b) 1.2N |
(c) 0.6N |
(d) 0.3N |
(d) 0.3N
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If the current 30 A flowing in the primary coil is made zero in 0.1 sec. The emf induced in the secondary coil is 1.5 volt. The mutual inductance between the coil is
|
(a) 0.05 H |
(b) 1.05 H |
(c) 0.1 H |
(d) 0.2 H |
As a result of interference of two coherent sources of light, energy is
|
(a) Increased |
|
(b) Redistributed and the distribution does not vary with time |
|
(c) Decreased |
|
(d) Redistributed and the distribution changes with time |
A photocell stops emission if it is maintained at 2V negative potential. The energy of most energetic photoelectron is
|
(a) 2eV |
(b) 2J |
(c) 2kJ |
(d) 2keV |