1. Light always travels in straight lines.   True   False   2. A lunar eclipse occurs when the earth comes between the sun and the moon.   True   False   3. If the power of a light source is measured in candelas and distance in meters, then the illuminance of the surface is in   Watt   Joule   Lux   Hint Half-n-half Clue   4. The SI unit of luminous intensity is _______.   Calorie   Candela   Coulomb   Half-n-half Clue   5. Materials through which objects can be seen clearly are said to be   transparent   translucent   opaque   Half-n-half Clue   6. _______ is a type of solar eclipse where the moon's shadow covers the sun's center and has a ring of sunlight around it.   A lunar eclipse   An annular eclipse   A helical eclipse   Half-n-half Clue   7. _______ is an instrument used to compare the luminous intensities of two sources of light.   Electroscope   Camera   Photometer   Half-n-half Clue