When visible light, X rays, gamma rays, or other forms of electromagnetic radiation are shined on certain kinds of matter, electrons are ejected. That phenomenon is known as the photoelectric effect. The photoelectric effect was discovered by German physicist Heinrich Hertz (1857–1894) in 1887. You can imagine the effect as follows: Suppose that a metal plate is attached by two wires to a galvanometer. (A galvanometer is an instrument for measuring the flow of electric current.) If light of the correct color is shined on the metal plate, the galvanometer may register a current. That reading indicates that electrons have been ejected from the metal plate. Those electrons then flow through the external wires and the galvanometer. HOPE THIS HELPED
If the solution is treated as an ideal solution, the extent of freezing
point depression depends only on the solute concentration that can be
estimated by a simple linear relationship with the cryoscopic constant:
ΔTF = KF · m · i
ΔTF, the freezing point depression, is defined as TF (pure solvent) - TF
(solution).
KF, the cryoscopic constant, which is dependent on the properties of the
solvent, not the solute. Note: When conducting experiments, a higher KF
value makes it easier to observe larger drops in the freezing point.
For water, KF = 1.853 K·kg/mol.[1]
m is the molality (mol solute per kg of solvent)
i is the van 't Hoff factor (number of solute particles per mol, e.g. i =
2 for NaCl).
According to the kinetic molecular theory, the pressure of a gas in a container will increase if the number of collisions with the container wall increases.
<u>Explanation:</u>
Keeping the volume of the vessel constant, if we increase the amount of gas in it; the pressure will increase.
This is because when the number of gas particles increases in that limited volume, they hit the walls of the container with more energy and hence, the overall pressure of the gas increases.
If we decrease the amount of gas in the vessel or increase the volume for the same amount of gas, the pressure decreases. As the pressure inside the vessel depends upon the gas supplied in the container.
Objects should be cooled before their mass is determined on a sensitive balance because it could damage the balance. Also, because it would give you wrong reading of the mass. Hot objects would warm the air around it. A warm air would expand and would produce convection as it rises causing to give the object a mass that is less than the actual. Another reason would be it would cause instability in the readings, the mass would fluctuate every now and then due to the convection currents around the object. It is always recommended to weigh the masses of objects that are in room temperature.
(length of a tennis court)