describe jj thomson cathode ray experiment quizlet

Describe jj thomson cathode ray experiment quizlet free#

In order to determine if the cathode ray consisted of charged particles, Thomson used magnets and charged plates to deflect the cathode ray. What happened when JJ Thomson placed a small magnet against his cathode ray tube? Thomson's method used both the electrostatic and magnetic deflection of the cathode rays. To investigate this question Thomson made measurements on the charge to mass ratio of cathode rays. “What are these particles? are they atoms, or molecules, or matter in a still finer state of subdivision” (p.

He deduced that the cathode rays were made up of negatively- charged particles. In the second experiment, he discovered that the charge in the cathode rays was negative. With the two terminal velocities obtained, the droplet's charge is calculated from the previous formula.In Thomson's first experiment, he discovered that cathode rays and the charge they deposited were intrinsically linked together.

This process could be repeated multiple times and allow average fall and rise times, and hence velocities, to be calculated. The time to rise through the selected distance is measured and allows the rising terminal velocity to be calculated. The power supply is then turned back on, and the droplet begins to rise. These two values are used to calculate the falling terminal velocity. Within the cell, a set distance has been marked, and the time for the selected droplet to fall through this distance is measured. A droplet is selected by the observer, who is watching through the microscope. The power supply is then turned off, and the drops begin to fall. After a very short time, this only leaves negatively charged droplets remaining in the cell. This causes negatively charged droplets to rise but also makes positively charged droplets fall quicker, clearing them from the cell. The power supply is then turned on (to a sufficiently high voltage). Multiple droplets of oil will now be falling through the cell. The cell valve is opened, oil is sprayed across the top of the cell, and the valve is then closed.

Describe jj thomson cathode ray experiment quizlet free#

The diagram below shows the forces and their directions that act on a droplet in two scenarios: when the droplet free falls and when an electric field causes the droplet to rise.įirstly, calibration is performed, such as focusing the microscope and ensuring the cell is level. As the droplets are very small, the droplets are reasonably assumed to be spherical in shape. To understand this motion, the forces acting on an individual oil droplet need to be considered. Millikan's experiment revolves around the motion of individual charged oil droplets within the cell.

The terminal velocity is the maximum speed the object will obtain while free falling through the fluid. At this point, the object is falling at a constant speed, which is called the terminal velocity. Eventually, these forces will balance (along with a buoyancy force), and therefore the object no longer accelerates. As a consequence of this increasing speed, the drag force acting on the object that resists the falling also increases. As an object falls through a fluid, such as air or water, the force of gravity will accelerate the object and speed it up.