choose correct one

1. An electromagnetic wave carries (a) no charge (b) no electric field (c) no magnetic field (d) none of the above. 2. An electromagnetic wave is (a) transverse wave (b) a longitudinal wave (c) a combination of both (d) all of the above. 3. Light is (a) the fastest object in the universe (b) is classically a wave (c) quantum mechanically a particle (d) all of the above. 4. The frequency of gamma rays is (a) greater than (b) lower than (c) equal to the frequency of radio waves (d) none of the above. 5. The wavelength of gamma rays is (a) greater (b) lower (c) equal to (d) none of the above than the wavelength of radio waves. 6. The image of a tree 20 meters from a convex lens with focal length 10 cm is (a) inverted (b) diminished (c) real (d) all of the above. 7. The image of an arrow 2 cm from a convex lens with a focal length of 5 cm is (a) erect (b) virtual (c) magnified (d) all of the above. 8. A parabolic mirror (a) focuses all rays parallel to the axis into the focus (b) reflects a point source at the focus towards infinity (c) works for radio waves as well (d) all of the above. 9. De Broglie waves (a) exist for all particles (b) exist only for sound (c) apply only to hydrogen (d) do not explain diffraction. 10. The Lorentz factor (a) modifies classical results (b) applies to geometric optics (c) is never zero (d) explains the Bohr model for hydrogen. 11. One of twins travels at half the speed of light to a star. The other stays home. When the twins get together (a) they will be equally old (b) the returnee is younger (b) the returnee is older (c) none of the above. 12. In Bohr's atomic model (a) the electron spirals into the proton (b) the electron may jump to a lower orbit giving off a photon (c) the electron may spontaneously jump to a higher orbit (d) all of the above