An electron beam is moving horizontally from east to west in a magnetic field directed downwards. In which direction will the beam be deflected by the field?

Hint:-According to Fleming’s right hand rule, the thumb shows the direction of force, the index finger shows the direction of velocity of the positive charge and the middle finger shows the direction of the magnetic field. The direction by which the beam is deflected can be found from this.

Complete Step by step answer:
The conductor carrying current will produce a magnetic field around it. This electromagnetic field will be surrounding the conductor. Also if we are bringing an external magnetic field close to the conductor, both the magnetic fields will interact. That is the electromagnetic field and the external magnetic field were interacting. Thus a force will be producing as a resultant. This force will be perpendicular to both the electromagnetic field and the magnetic field.

We have given that the electron beam is moving in a direction horizontally from east to west. And the direction of the magnetic field is downwards. The direction of the force will be perpendicular to both the directions. That is, it points toward the north direction. But here we have given an electron beam. For the electron is negatively charged the direction is opposite to a positive charge. Therefore the direction of the electron beam will be deflected in the direction south. Thus it will be deflected downwards.

Note: We have to note that the direction of the negative charge will be opposite to the positive charge. Fleming’s left hand is described for positive charges hence the conventional current is flow of positive charges.