- ✓spherical wavefront
- Bcylindrical wavefront
- Cboth (a) and (b)
- Dnone of these
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If are the lengths of the emitter, base and collector of a transistor then
|
(a) |
(b) |
(c) |
(d) |
If a long hollow copper pipe carries a direct current, the magnetic field associated with the current will be
|
(a) Only inside the pipe |
(b) Only outside the pipe |
|
(c) Neither inside nor outside the pipe |
(d) Both inside and outside the pipe |
Half lives of two radioactive substances A and B are respectively 20 minutes and 40 minutes. Initially the sample of A and B have equal number of nuclei. After 80 minutes, the ratio of remaining number of A and B nuclei is
|
(a) 1 : 16 |
(b) 4 : 1 |
(c) 1 : 4 |
(d) 1 : 1 |
The condition for a uniform spherical mass m of radius r to be a black hole is [G = gravitational constant and g = acceleration due to gravity]
|
(a) |
(b) |
(c) |
(d) |
A circular metal plate of radius R is rotating with a uniform angular velocity ω with its plane perpendicular to a uniform magnetic field B. Then the emf developed between the centre and the rim of the plate is
|
(a) πω |
(b) ω |
(c) πω |
(d) ω |
If a proton is projected in a direction perpendicular to a uniform magnetic field with velocity v and an electron is projected along the lines of force, what will happen to proton and electron
|
(a) The electron will travel along a circle with constant speed and the proton will move along a straight line |
|
(b) Proton will move in a circle with constant speed and there will be no effect on the motion of electron |
|
(c) There will not be any effect on the motion of electron and proton |
|
(d) The electron and proton both will follow the path of a parabola |