A variable condenser is permanently connected to a 100 V battery. If the capacity is changed from 2μF to 10 μF, then change in energy is equal to
|
(a) 2 |
(b) 2.5 |
(c) 3.5 |
(d) 4 |
(d) 4 
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The time period of oscillation of a freely suspended bar magnet with usual notations is given by
(a) T = 2π
|
(b) T = 2π
|
(c) T =
|
(d) T = 2π
|
A TV tower has a height of 100 m. The average population density around the tower is 1000 per km2. The radius of the earth is 6.4 
m. the population covered by the tower is
|
(a) 2 |
(b) 3 |
(c) 4 |
(d) 6 |
Electric charges of +10μC, + 5μC, -3μC and +8 μC are placed at the corners of a square of side 
m. the potential at the centre of the square is
|
(a) 1.8 V |
(b) |
(c) 1.8 |
(d) 1.8 |
A magnetic needle is made to vibrate in uniform field H, then its time period is T. If it vibrates in the field of intensity 4H, its time period will be
| (a) 2T | (b) T/2 | (c) 2/T | (c) 2/T |
An electron in the n = 1 orbit of hydrogen atom is bound by 13.6 eV energy is required to ionize it is
|
(a) 13.6 eV |
(b) 6.53 eV |
(c) 5.4 eV |
(d) 1.51 eV |
