Place a straight wire horizontally between the poles of a strong magnet so that it lies at 90° to the magnetic field. Connect the wire to a DC power supply through a switch. When the current flows, the wire will experience a force and move.
This demonstrates the motor effect and the force which moves the object is known as the Lorentz force. Reversing the current or magnetic field reverses the direction of the force:
There are two mnemonics that help us determine the relative directions of current, magnetic field and the force: the Right-Hand Palm Rule, which was used in the video above, and Fleming's Left-Hand Rule.
The Right-Hand Palm Rule is a helpful mnemonic used to determine the direction of the force acting on a current when it travels through a magnetic field. Use your right hand with the palm and fingers straightened:
Fleming’s Left-Hand Rule helps determine the direction of the force acting on a current-carrying conductor placed at right angles to a magnetic field. Use your left hand:
By aligning any two of these quantities at right angles, you can determine the third.
Note: as we are dealing with vectors in 3-dimensions, we need to introduce two symbols for when the vectors cannot be represented on a plane surface such as the screen of the device you are using right now, or the piece of paper on which these vectors are drawn. A cross represents a vector with direction into the plane while a circle with a dot represents a vector with direction coming out of the plane.
Vector going away (image on left) and vector coming towards you (image on right)