Wavefront means
|
(a) All particles in it have same phase |
|
(b) All particles have opposite phase of vibrations(c) Few particles are in same phase, rest are in opposite phase |
|
(c) Few particles are in same phase, rest are in opposite phase |
|
(d) None of these |
(a) All particles in it have same phase
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If 
is the original mass of the substance of half life period 
years, then the amount of substance left after 15 years is
|
(a) |
(b) |
(c) |
(d) |
For sky wave propagation of a 10 MHz signal, what should be the minimum electron density in ionosphere
|
(a) ~ 1.2 × 1012 m–3 |
(b) ~ 106 m–3 |
(c) ~ 1014 m–3 |
(d) ~ 1022 m–3 |
When the speed of electrons increases, then the value of its specific charge
|
(a) Increases |
|
(b) Decreases |
|
(c) Remains unchanged |
|
(d) Increases upto some velocity and then begins to decrease |
In Thomson's experiment if the value of q/m is the same for all positive ions striking the photographic plate, then the trace would be
|
(a) Straight line |
(b) Parabolic |
(c) Circular |
(d) Elliptical |
The plate current ip in a triode valve is given 
where ip is in milliampere and Vp and Vg are in volt. If rp = 104 ohm, and 
, then for 
and 
, what is the value of K and grid cut off voltage
|
(a) – 6V, (30)3/2 |
(b) -6 V, |
(c) + 6V, (30)3/2 |
(d) + 6V, (1/30)3/2 |
