Physics Online Quiz

Hydrogen is lighter than air. When a balloon is filled with hydrogen gas the weight of the balloon is less than the weight of air displaced by the balloon.

The Indian Space Research Organisation (ISRO) is the national space agency of India, headquartered in Bengaluru. ISRO was formed on 15 August 1969. Dr. Vikram A Sarabhai is considered as the founding father of space programmes in India.

The time period of a pendulum is directly proportional to the square root of its length. So when its length is halved, its time period is decreased by a factor. If the length L of a simple pendulum is halved, then its period of oscillation will decrease by √2÷2.

Clear nights are colder than cloudy nights because of radiation. Clouds warm the Earth by absorbing infrared radiation emitted from the surface and reradiating it back down.

Isohyte is a line on a map connecting points having the same amount of rainfall in a given period. Isobar is a line on a map that joins places that have the same air pressure at a particular time. Isohel is a line on a map connecting points having the same duration of sunshine. Isotherm a line on a map that joins places that have the same temperature at a particular time.

When a ship enters the sea from a river it rises a little because seawater has more density than river water. Due to the higher density of seawater, the upthrust produced by the seawater on the ship is greater as compared to that produced by river water.

When a vibrating tuning fork is placed on a table, a loud sound is heard due to forced vibrations. The tendency of one object to force another adjoining or interconnected object into vibration motion is referred to as forced vibration.

Aluminium and its alloys are used for making aircraft and rockets, due to their high strength at relatively low density.

The atmospheric air is held to the Earth by gravity. Earth's gravity is strong enough to hold onto its atmosphere and keep it from drifting into space.

Telescope and microscope can be distinguished by observing the length and size of the lens. In a telescope, the object lens has a large focal length and large aperture and the eye lens has small focal length and small aperture. The distance between the object lens and eye lens is adjusted to focus on the object situated at infinity. In a microscope, the object lens has a small focal length and short aperture and the eye lens used has a moderate focal length and large aperture. The object and eye lens are kept at a fixed distance apart, whereas the distance of the objective lens from the object is adjusted to focus an object.