The danger signals installed at the top of tall buildings are red in colour. These can be easily seen from a distance because among all other colours, the red light

Why are danger signals red in colour ?

Why are the 'danger signal' lights red in colour ?

In an experiment, Pooja used a equilateral triangular glass prism and projected a narrow beam of white light source from one side of the surface of the prism. She placed a screen on the other side and saw many colours appearing as patches on the screen. But when she used a red light source, she could only see a red patch on the screen. Similarly she used a blue and green light source and could only see one colour patch on both occasions. The reason why she could no see any other colour when the red light was used was because:

Seven men-A, B, C, D, E, F and G are standing in a queue in that order. Eachone is wearing a cap of different colour violet, indigo, blue, green, yellow, orange and red. D is able to see in front of him green and blue, but not violet. F can see violet and yellow, but not red. G can see caps of all the colours other than orange. If E is wearing an indigo coloured cap, then the colour of the cap worn by F is

The cost of the red green and blue colours per kg is ₹20 ₹15 and ₹18 respectively. Rang mahal is a renowned building in which these three colours are being used in the ratio of 3:2:4.The average cost of all the three colours used per kg is:

The cost of the Red, Green and Blue colours per kg is Rs. 20, Rs. 15 and Rs. 18 respectively. Rang Mahal is a renowned building in which these three colours are being used in the ratio of 3 : 2 : 4. The average cost of all the three colours used per kg is :