cameroon gce A level June 2017 physics 1
In the photoelectric effect, electromagnetic waves incident upon the surface of a metal can cause electrons to be emitted by it. Which of the following will result in more electrons being emitted per second?
A Using a different metal
B Using the same intensity of radiation, but of a shorter wavelength
C Using the same intensity of radiation, but of a higher frequency
D Using more intense radiation of the same wavelength
4 Two identical, hard , spherical balls X and Y each of mass m , are travelling in opposite directions, with the same speed u. If they collide elastically on a friction – free surface, which of the statements below best describes their motion?
A They stick together on impact, and
instantaneously come to rest
B The total energy of the system is conserved
C The energy before collision is greater than
that after collision
D The total kinetic energy just after impact is mu 2
Which of the following statements about a moving body is NOT correct?
A Even without a body accelerating, it is possible for its speed to change
B Whenever the speed of the body changes, its velocity equally changes
C If the body has a constant, it is possible for it to have an acceleration
9. Which of the following can effectively low‘er the internal energy of a room?
A A fan
B A refrigerator with its door left wide open
C An air – conditioner partially exposed to the atmosphere
D A refrigerator with its door close
