Physics Online Quiz

Woollen clothes keep the body warm because wool is a bad conductor of heat. Woollen clothes are thick and trap air inside forming a layer around the body and so it does not let our body temperature decrease through conduction.

The loss of water in the form of water droplets is called guttation. Guttation is the exudation of drops of xylem sap on the tips or edges of leaves of some vascular plants, such as grasses, and a number of fungi.

The angle of friction and angle of repose are equal to each other. The angle which the resultant of force of limiting friction F and normal reaction R makes with direction of normal reaction R is called angle of friction. Angle of repose is the steepest angle at which a sloping surface formed of loose material is stable.

A simple microscope is a magnifying glass that has a single or double convex lens with a short focal length.

Apollo 11 was the first manned mission to land on the Moon. The first steps by humans on another planetary body were taken by Neil Armstrong and Buzz Aldrin on July 20, 1969.

Most of the ultraviolet radiation in sunlight is absorbed by oxygen in Earth's atmosphere, which forms the ozone layer of the lower stratosphere.

A spherical ball made of steel when dropped in a mercury container will be on the surface of mercury because the density of mercury is higher than that of steel.

A concave lens is used to minimize the proportions of the objects and gives a wider view of the object or area. It always forms virtual, erect and diminished image.

Stars have different colours, which are indicators of temperature. The hottest stars tend to appear blue or blue-white, whereas the coolest stars are red.

When warm air (over the fire spot) rises, the air pressure at that place gets lowered. But around it, pressure is high so the air rushes from high-pressure zone to low-pressure zone giving an appearance of fanning the fire.