1
MCQ (Single Correct Answer)
Two charged particles traverse identical helical paths in a completely opposite sense in a uniform magnetic field $\mathbf{B}=B_0 \hat{\mathbf{k}}$.
A
They have equal z-components of momenta
B
They must have equal charges
C
They necessarily represent a particle, anti-particle pair
D
The charge to mass ratio satisfy $$\left(\frac{e}{m}\right)_1+\left(\frac{e}{m}\right)_2=0$$
2
MCQ (Single Correct Answer)
Biot-Savart law indicates that the moving electrons (velocity $v$ ) produce a magnetic field $\mathbf{B}$ such that
A
B is perpendicular of
B
$B$ is parallel to $v$
C
it obeys inverse cube law
D
it is along the line joining the electron and point of observation
3
MCQ (Single Correct Answer)
A current carrying circular loop of radius R is placed in the $x$-y plane with centre at the origin. Half of the loop with $x>0$ is now bent so that it now lies in the $y-z$ plane.
A
The magnitude of magnetic moment now diminishes
B
The magnetic moment does not change
C
The magnitude of B at $(0,0, \mathrm{z}), \mathrm{z}>R$ increases
D
The magnitude of B at $(0,0, z), \mathrm{z} \gg>R$ is unchanged
4
MCQ (Single Correct Answer)
An electron is projected with uniform velocity along the axis of a current carrying long solenoid. Which of the following is true?
A
The electron will be accelerated along the axis
B
The electron path will be circular about the axis
C
The electron will experience a force at $45^{\circ}$ to the axis and hence execute a helical path
D
The electron will continue to move with uniform velocity along the axis of the solenoid
5
MCQ (Single Correct Answer)
In a cyclotron, a charged particle
A
undergoes acceleration all the time
B
speeds up between the dees because of the magnetic field
C
speeds up in a dee
D
slows down within a dee and speeds up between dees