For a positively charged particle moving in a `x-y` plane initially along the `x-axis` , there is a sudden change in its path due to the presence of electric and//or magnetic fields beyond `p` . The curved path is shown in the ` x- y `plane and is found to be non - circular. Which one of the following combinations is possible ?

Options

A. `vec E = 0, vec B = b hat I + c hat k`
B. `vec E = a hat I , vec B = c hat k + b hat i`
C. `vec E = 0, vecB = c hat j + b hat k`
D. `vec E = a hat I , vec B = c hat k + b hat j`.

Answer

a, b

Explanation

There is a sudden change in the path. In all options either `E= 0 `or it is along X-axis, hence the deflection is due to magnetic force only. Velocity along X-axis is not affected by the component of magnetic field along X-axis. Moreover, the immediate path followed by the particle is on - plane hence the y-component of magnetic field is not desirable. Thus, options (a) and (b) are possible.