1. _______ is an instrument used to compare the luminous intensities of two sources of light.   Electroscope   Camera   Photometer   Hint Half-n-half Clue   2. Materials through which light cannot pass are said to be   transparent   translucent   opaque   Half-n-half Clue   3. Light always travels in straight lines.   True   False   4. A _______ beam is one whose rays remain the same distance apart.   convergent   parallel   divergent   Half-n-half Clue   5. The SI unit of luminous intensity is _______.   Calorie   Coulomb   Candela   Half-n-half Clue   6. Illuminance of a surface is proportional to the power of the light source and inversely proportional to the square of the _______.   luminous intensity   area   distance   Half-n-half Clue   7. Materials through which objects can be seen clearly are said to be   transparent   translucent   opaque   Half-n-half Clue