a monochromatic light beam is incident on a barium target that has a work function of 2.50 ev. if a potential difference of 1.00 v is required to turn back all the ejected electrons, what is the wavelength of the light beam?

Dry ice is solid carbon dioxide that is used in the transport of food and medicine. dry ice becomes a gas at –78.5°c without becoming a liquid first.

Scientists use laser range-finding to measure the distance to the moon with great accuracy. a brief laser pulse is fired at the moon, then the time interval is measured until the "echo" is seen by a telescope. a laser beam spreads out as it travels because it diffracts through a circular exit as it leaves the laser. in order for the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1.0 km in diameter. staying within this diameter is accomplished by using a special large-diameter laser. part a if λ = 540nm , what is the minimum diameter of the circular opening from which the laser beam emerges? the earth-moon distance is 384,000 km. express your answer to two significant figures and include the appropriate units.

Anybody wanna ? (picture included? )