If V be the accelerating voltage, then the maximum frequency of continuous X-rays is given by
(a) 
|
(b) 
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(c)
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(d) 
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Broadcasting antennas are generally
|
(a) Omnidirectional type |
(b) Vertical type |
(c) Horizontal type |
(d) None of these |
In a vibration magnetometer, the time period of a bar magnet oscillating in horizontal component of earth's magnetic field is 2 sec. When a magnet is brought near and parallel to it, the time period reduces to 1 sec. The ratio H/F of the horizontal component H and the field F due to magnet will be
| (a) 3 | (b) 1/3 |
(c) 
|
(d) 1/
|
Decay constant of radium is λ. By a suitable process its compound radium bromide is obtained. The decay constant of radium bromide will be
|
(a) λ |
(b) More than λ |
(c) Less than λ |
(d) Zero |
Missing lines in a continuous spectrum reveal
|
(a) Defects of the observing instrument |
|
(b) Absence of some elements in the light source |
|
(c) Presence in the light source of hot vapours of some elements |
|
(d) Presence of cool vapours of some elements around the light source |
Quantity that remains unchanged in a transformer is
|
(a) Voltage |
(b) Current |
(c) Frequency |
(d) None of the above |
In Fig. X represents time and Y represent activity of a radioactive sample. Then the activity of sample, varies with time according to the curve
|
(a) A |
(b) B |
(c) C |
(d) D |