1) Which of the following mirror is used by a dentist to examine a small cavity? a) Convex mirror b) Plane mirror c) Concave mirror d) Combination of convex and concave mirror 2) The angle of incidence i and refraction r are equal in a transparent slab when the value of i is a) 0° b) 45° c) 90° d) none of these 

physics

由
打印
嵌入

排行榜

视觉风格

选项

切换模板

恢复自动保存：？