What is the tall device which contains plane mirror and can be used to see over the heads of crowds ( say,as in a football match)
A student makes a device P by using three long and narrow strips of plane mirrors inclined at 60∘ to one another which enables him to see beautiful pattern made by pieces of coloured glass bangles. On the other hand, another student makes a device Q by using two plane mirrors arranged parallel to each other which helps him to see a football match clearly even when some very tall persons are sitting in front of him in the ground. What are P and Q?
What device other than a plane mirror can be used to turn a ray of light through 180∘ ? Draw a diagram in support of your answer. Name an instrument in which this device is used.