An electron initially at rest, is accelerated through a potential difference of 200 volt, so that it acquires a velocity 8.4 
. The value of e/m of electron will be
|
(a) 2.76 |
(b) 1.76 |
(c) 0.76 |
(d) None of these |
(b) 1.76 
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When a piece of a ferromagnetic substance is put in a uniform magnetic field, the flux density inside it is four times the flux density away from the piece. The magnetic permeability of the material is
|
(a) 1 |
(b) 2 |
(c) 3 |
(d) 4 |
If the energy of a hydrogen atom in nth orbit is 
, then energy in the nth orbit of a singley ionized helium atom will be
|
(a) 4
|
(b) 
|
(c) 2
|
(d) 
|
Electrical conductivity of a semiconductor
|
(a) Decreases with the rise in its temperature |
|
(b) Increases with the rise in its temperature |
|
(c) Does not change with the rise in its temperature |
|
(d) First increases and then decreases with the rise in its temperature |
As in figure shown, if a capacitor C is charged by connecting it with resistance R, then energy is given by the battery will be
|
(a) |
(b) More than |
(c) Less than |
(d) Zero |
An ammeter gives full scale deflection when current of 1.0 A is passed in it. To convert it into 10 A range ammeter, the ratio of its resistance and the shunt resistance will be
|
(a) 1 : 9 |
(b) 1 : 10 |
(c) 1 : 11 |
(d) 9 : 1 |
The mass equivalent of 931 MeV energy is
|
(a) 1.66 |
(b) 6.02 |
(c) 1.66 |
(d) 6.02 |
The half-life of a radioactive substance is 40 years. How long will it take to reduce to one fourth of its original amount and what is the value of decay constant
| (a) 40 year, 0.9173/year | (b) 90 year, 9.017/year |
| (c) 80 year, 0.0173 year | (d) None of these |
A charge of 
is placed on each of the 64 identical drops of radius 2cm. They are then combined to form a bigger drop. Find its potential
|
(a) 7.2 |
(b) 7.2 |
(c) 1.44 |
(d) 1.44 |
