A xenon arc lamp is covered with an interference filter that only transmits light of 400-nm wavelength. When the transmitted light strikes a metal surface, a stream of electrons emerges from the metal. The interference filter is then replaced with one transmitting at 300 nm and the lamp adjusted so that the intensity of the light striking the surface is the same as it was for the 400-nm light. With the 300- nm light 1. more electrons are emitted in a given time interval. 2. the electrons which are emitted are more energetic 3. both are true. 4. both are false. Please choose from 1-4, explaining your answer.

3. both are true.

Explanation:

Energy increses with decrease in wavelenght.

For photoemission to occur, a threshold energy barrier must be broken.

Higher energy means more electrons will be emmited.

The electrons emmited will posses energy that is less than the incident energy by the value of the threshold energy.

So the higher the energy, the higher the energy possessed by the electrons.

from 1609, galileo galilei used the recently invented telescope to observe the sun, moon and planets. he saw the mountains and craters of the moon, and for the first time revealed the planets to be worlds in their own right. galileo also provided strong observational evidence that planets orbited the sun.

his discoveries about the moon, jupiter's moons, venus, and sunspots supported the idea that the sun - not the earth - was the center of the universe, as was commonly believed at the time.galileo turned his gaze toward venus, the brightest celestial object in the sky - other than the sun and the moon.