Højrehåndsreglen

Højrehåndsreglen is a mnemonic rule used in physics and electromagnetism to determine the direction of vector products and related phenomena. It is particularly useful when dealing with quantities like magnetic forces, torque, and angular momentum.

The rule is applied by using the thumb, index finger, and middle finger of the right hand, which are held mutually perpendicular to each other. The specific application of the rule depends on the context. For example, when determining the direction of the force on a current-carrying wire in a magnetic field, the index finger points in the direction of the current, the middle finger points in the direction of the magnetic field, and the thumb then points in the direction of the force.

Alternatively, for vector cross products, such as the angular momentum L = r x p, where r is the position vector and p is the linear momentum, the index finger points along the first vector (r), and the middle finger points along the second vector (p). The thumb then points in the direction of the resulting vector (L).

There are variations of the right-hand rule for different situations, such as determining the direction of the magnetic field around a current-carrying wire. In this case, the thumb points in the direction of the current, and the curled fingers indicate the direction of the magnetic field lines. The consistency of the right-hand rule across various physics principles makes it a fundamental tool for understanding three-dimensional vector relationships.