A computer program is a set of instructions or code written by a programmer to perform a specific task. When you press the J key on your keyboard, it sends an electrical signal to the computer's processor. The processor interprets this signal and executes the corresponding code for the J key, which is typically stored in the computer's memory. The code may include instructions to display the letter J on the screen, so the processor sends a signal to the graphics card. The graphics card then converts the signal into pixels and sends it to the display monitor, which ultimately displays the letter J on the screen.
The exact path that the electrical signal takes may vary depending on the specific hardware and software configuration of your computer. However, generally, the signal will travel from the keyboard to the processor, then to the memory, graphics card, and finally to the display monitor. It is important to note that modern computers are extremely complex and have multiple components working together to execute a single task, so the signal may also travel through other components such as the motherboard and input/output devices.
In summary, a computer program works by interpreting and executing code to perform a specific task, and the physical path of an electrical signal involves multiple components working together to display the desired output on the screen.