Learning to apply the rule of the left hand

Physics is by far not the easiest subject, especially for those who have problems with exact sciences. It's not a secret that not everyone gets along with sign systems, there are people who need to touch or at least see what they are studying. Fortunately, in addition to formulas and boring books, there are also clear ways. For example, in this article, we will consider how to determine the direction of electromagnetic force with the help of the hand, using the known rule of the left hand.

This rule makes it a little easier if not understanding the laws, then at least solving problems. True, only those who understand at least a little knowledge of physics and its terms will be able to apply it. In many textbooks there is an image, very intelligibly explaining how to apply the rule of the left hand in solving problems. Physics, however, is clearly not the kind of science where you often have to put your hand to visual patterns, so develop your imagination.

First, you need to know the direction of the current flow in the part of the circuit where you are going to apply the rule of the left hand. Remember that an error in determining the direction will show you directly the opposite direction of the electromagnetic force, which will automatically nullify all your further efforts and calculations. As soon as you determine the direction of the current, place your left hand so that your fingers indicate this course.

Next, find the direction of the vector of magnetic induction. If you have any problems with this, it is worthwhile to refresh your knowledge with the help of textbooks. When you find the desired vector, turn the palm so that the given vector enters the open palm of the same left hand. The whole difficulty of applying the rule of the left hand is precisely whether you can correctly apply your knowledge to find constant vectors.

When you are sure that your palm is properly positioned, pull the thumb out so that its position becomes perpendicular to the current direction (where the other fingers of the bunch point out). Remember that the finger is not the most accurate indicator in physics, and in this case it shows only an approximate direction. If you are interested in accuracy, then after applying the rule of the left hand, use the protractor to bring the angle between the current direction and the direction indicated by the thumb to 90 degrees.

It should be remembered that the rule in question is not suitable for accurate calculations - it can only serve to quickly determine the direction of the electromagnetic force. In addition, its use requires additional conditions of the problem, and therefore is not always applicable in practice.

Naturally, it is not always possible to put a hand on the object under study, since sometimes it does not exist at all (in theoretical problems). In this case, in addition to the imagination, other methods should be used. For example, you can draw a diagram on paper and apply the rule of the left hand to the drawing. The hand itself can also be schematically depicted in the figure for greater visibility. The main thing is not to get confused in the vectors, otherwise you can make mistakes. So do not forget to mark all the lines with signatures - then it will be easier to understand yourself later.