What is the pulse? Pulse is the pulsation of the arteries caused by the action of the heart. It can be felt at any artery which can be felt through the skin. The pulse rate indicates how fast the heart is beating and the state...
How do experts classify dinosaurs? Dinosaurs are divided into two groups based on their hip shapes. Sauropods were plant-eaters and had lizard hips. They walked on four legs. Theropods were meat-eaters and had two legs. They too had lizard hips. Bird-hipped dinosaurs which ate plants...
What is the origin of the Christmas tree? The Christmas tree is more a tradition than a religious observance. It symbolises the spirit of Yuletide in many homes. The tradition originated in Germany. In the old days, the pagans worshipped trees but Christians changed the...
Who invented traffic signals? The first traffic controllers were foot patrolmen. Initially they directed traffic using their hands and later they used hand-operated traffic lights. In the early 1920s automatic traffic lights were used for the first time. In 1927, traffic-actuated controllers were patented. These...
What is the significance of April Fools’ Day? On April Fools’ Day we play practical jokes on friends and relatives. Some think the French started it. In 1564, Charles IX decreed that the New Year should begin on January 1st. Until then April 1st was...
What are bacteria? Bacteria are felt to be the lowest members of the plant kingdom. A bacterium is a single piece of living matter which has no nucleus. Bacteria have many roles to play. Some cause plants and animals to decay while others cause fermentation....
What makes a waterfall? Waterfalls are caused by a stream or river plunging over a wall of rock like a cliff or a precipice. A big size waterfall is called a cataract. If the rock wall is slanted, the flowing water is called a cascade....
Why are even-numbered pages always on the left? In a book, the first left hand page is the second side of the first right hand page. If that page is the first page, then it must be page 2 on its other side and every...
Why do our ears ring sometimes? The ringing sound in our ears we sometimes experience is called tinnitus. One reason for it is a bad connection between the inner ear and the brain. The inner ear contains hair cells. Damage to these cells makes them...
How is humidity measured? Humidity is the amount of water vapour in the atmosphere. If the relative humidity is 80%, it means that the air is holding 80% of the water vapour it can hold. A hygrometer is used to measure humidity.
