An ionization chamber with parallel conducting plates as anode and cathode has 5 
electrons and the same number of singly-charged positive ions per 
. The electrons are moving at 0.4 m/s. The current density from anode to cathode is 
. The velocity of positive ions moving towards cathode is
|
(a) 0.4 m/s |
(b) 16 m/s |
(c) Zero |
(d) 0.1 m/s |
(d) 0.1 m/s
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The ratio activity of an element becomes 1/64th of its original value in 60 sec. Then the half life period is
|
(a) 5 sec |
(b) 10 sec |
(c) 20 sec |
(d) 30 sec |
The essential distinction between X-rays and γ - rays is that
| (a) γ- rays have smaller wavelength than X-rays |
|
(b) γ - rays emanate from nucleus while X-rays emanate from outer part of the atom |
| (c) γ- rays have greater ionizing power than X-rays |
| (d) γ- rays are more penetrating than X-rays |
The radii of two metallic spheres P and Q are 
and 
respectively. They are given the same charge. If 
. then on connecting them with a thin wire, the charge will flow
|
(a) From P to Q |
|
(b) From Q to P |
|
(c) Neither the charge will flow from P to Q nor from Q to P |
|
(d) The information is incomplete |
X-rays of which of the following wavelengths are hardest
| (a) 4 Å | (b) 1 Å | (c) 0.1 Å | (d) 2 Å |
Assertion : The speed of light in a rarer medium is greater than that in a denser medium
Reason : One light year equals to 9.5 × 1012 km
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |