1.For an isotropic radio source which is located 90 km away has an intensity 5.6 * 10-6 W/m2. What is the average power emitted by the source?

2. A mirror is tilted at an angle of 30 degrees to the bench. A ray of light is directed so that is hits the mirror at an angle of 40 degrees to the surface of the mirror at an angle of reflection. What is the angle of reflection?

3.an object 5cm high us 35cm in front of a mirror whose focal length is -50cm what is the height of the image?

5. a diffracted grafting difracts light at 15 degrees what is the wave length of the light if the grafting has 1000 lines per mm?

6a speed of light inair is 3.0 times 10 to the power of 8 m/s if the the light of speed in a material A is 2.5 times 10 to the power of 8 calculate the refractive index of the material A.