3. A star in a distant galaxy approaches the Sun at 3 X 106 m/s. It emits a photon with a wave- length of 0.4 microns. Apply the Doppler Effect to estimate the observed wavelength of this pho- ton.
4. An object is 2 meters from a thin lens with a focal length of 50 cm. Apply the thin-lens equa- tion to calculate the image distance from the lens and magnification.