Answer:
(b) EAST
Explanation:
you can assume that the magnetic field points rightward, that is, in the positive x direction (NORTH). Furthermore, you can assume that the direction of the motion of the electron is in the positive y direction. Hence, you have:

You use the Lorentz formula to known which is the direction of the magnetic force over the electron:

which implies the cross product between the unitary vecors j and i, that is
(WEST)
However, the minus sign of the charge of the electron changes the direction 180°. Hence, the direction is k. That is, to the EAST
Answer:
Part a)
Width of the slit is

Part b)
Ratio of intensity is given as

Explanation:
Part a)
As we know by the formula of diffraction we will have

so we have


so we will have


Part b)
As we know that the intensity in diffraction pattern is given as


so for angle 45 degree



The motion of the light is a uniform motion with constant speed

, therefore we can use the basic relationship between speed, space and time:

(1)
where S is the distance covered and t is the time taken. The light takes t=1.3 s to travel from the moon to Earth, therefore by rearranging eq.(1) we can find the distance between the Moon and the Earth: