1. Materials that allow light to pass but through which objects cannot be clearly seen are said to be   translucent   transparent   opaque   Hint Half-n-half Clue   2. Light always travels in straight lines.   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   Lux   Joule   Watt   Half-n-half Clue   4. The partly lighted area of a shadow on the periphery of the totally shaded portion is called the _______   eclipse   umbra   penumbra   Half-n-half Clue   5. A _______ beam is one whose rays remain the same distance apart.   divergent   parallel   convergent   Half-n-half Clue   6. A _______ eclipse occurs when the moon comes between the sun and the earth.   solar   lunar   7. A lunar eclipse occurs when the earth comes between the sun and the moon.   True   False