If an electron moves from rest from a point at which potential is 50 volt to another point at which potential is 70 volt, then its kinetic energy in the final state will be
|
(a) 3.2 × 10–10 J |
(b) 3.2 × 10–18 J |
(c) 1 N |
(d) 1 dyne |
(b) 3.2 × 10–18 J
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Two coherent light sources S1 and S2 (l= 6000 Å) are 1mm apart from each other. The screen is placed at a distance of 25 cm from the sources. The width of the fringes on the screen should be
|
(a) 0.015 cm |
(b) 0.025 cm |
(c) 0.010 cm |
(d) 0.030 cm |
The half-life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after
|
(a) 2400 years |
(b) 3200 years |
(c) 4800 years |
(d) 6400 years |
The decay constant of radium is 4.28 
per year. Its half life will be
|
(a) 2000 years |
(b) 1240 years |
(c) 63 years |
(d) 1620 years |
On the bombardment of neutron with Boron. a-particle is emitted and product nuclei formed is
|
(a) |
(b) |
(c) |
(d) |
Armature current in dc motor will be maximum when
|
(a) Motor has acquired maximum speed |
(b) Motor has acquired intermediate speed |
|
(c) Motor has just started moving |
(d) Motor is switched off |
A circular disc of which 2/3 part is coated with yellow and 1/3 part is with blue. It is rotated about its central axis with high velocity, then it will be seen as
|
(a) Green |
(b) Brown |
(c) White |
(d) Violet |
