In which direction Cathode rays deflected in the presence of magnetic field?

Explanation

Cathode rays (which are streams of electrons) are deflected perpendicular to both the magnetic field and their direction of motion when placed in a magnetic field.According to Fleming's Left-Hand Rule:Thumb: Direction of force (deflection)First finger: Direction of magnetic fieldSecond finger: Direction of current (or electron motion - opposite to conventional current)Since cathode rays are negatively charged particles (electrons), they experience a force opposite to the direction of current.So, the deflection depends on:Direction of the magnetic fieldDirection of cathode ray motionExample:If cathode rays move horizontally from left to rightAnd magnetic field is applied vertically downward → Then cathode rays will deflect out of the page (toward the observer)Thus, the deflection is always perpendicular to both the magnetic field and the electron motion, and the exact direction can be determined using Fleming's Left-Hand Rule.