Explanation:
The X-ray beam emerging from an X-ray tube consists of wavelengths greater than a certain minimum wavelength called cutoff wavelength.
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$\text{v}$
$\frac{\text{v}}{2}$
$2\text{v}$
$\sqrt{2}\text{v}.$
Curie is a unit of
|
(a) Length |
(b) It is not any unit |
(c) Activity |
(d) Atomic number |
The new resistance of wire of R W, whose radius is reduced half, is
|
(a) 16 R |
(b) 3 R |
(c) 2R |
(d) R |
For a real object, which of the following can produced a real image
|
(a) Plane mirror |
(b) Concave lens |
(c) Convex mirror |
(d) Concave mirror |
A radioactive sample has 
active atoms at t = 0. If the rate of disintegration at any time is R and the number of atoms is N, then the ratio R/N varies with time as
|
(a)
|
(b)
|
(c)
|
(d)
|
An electron moving towards the east enters a magnetic field directed towards the north. The force on the electron will be directed
|
(a) Vertically upward |
(b) Vertically downward |
|
(c) Towards the west |
(d) Towards the south |
The distance between the plates of a parallel plate condenser is 4mm and potential difference is 60 volts. If the distance between the plates is increased to 12mm, then
|
(a) The potential difference of the condenser will become 180 volts |
|
(b) The P.D. will become 20 volts |
|
(c) The P.D. will remain unchanged |
|
(d) The charge on condenser will reduce to one third |
