General Science GK Questions with Answers – Page 119

A centre-tap full wave rectifier needs two p-n junction diodes, one for each half of the input cycle. The secondary winding of the transformer is tapped at its middle, so its two halves give equal voltages of opposite sign.

At normal atmospheric pressure water stays liquid between 0 °C and 100 °C, and 12 °C lies inside that range.

Kinetic energy depends on the square of the momentum, so the momentum grows as the square root of the energy.

A silicon diode in forward bias drops about 0.7 volt across itself, whatever the supply voltage is.

The stamen and the pistil make the male and female gametes, so they are the essential or reproductive organs of a flower.

Silver is a noble metal and does not combine with oxygen even when it is heated strongly. Metals react with oxygen according to their place in the reactivity series.

The ball falls from 10 m but rises back only 2.5 m, so it keeps one quarter of its energy and loses three quarters.

Moss, or Funaria, and Marchantia, a liverwort, are bryophytes, the group called the amphibians of the plant kingdom because they live on land but need water for reproduction.

If each length of a solid grows by a certain small fraction when it is heated, an area, which is the product of two lengths, grows by about twice that fraction, and a volume, the product of three lengths, by about three times.

An adiabatic change is one in which no heat is exchanged with the surroundings.

A cooker is sealed, so the steam it produces cannot escape and the pressure inside rises. Since the boiling point of a liquid rises with the pressure on it, water in a cooker boils well above a hundred degrees Celsius, and food cooking at that higher temperature is ready sooner.

The efficiency of an ideal Carnot engine is one minus the ratio of the sink temperature to the source temperature, both in kelvin.

The space between the sun and the earth is very nearly empty, and radiation is the only mode of heat transfer that needs no material medium: energy travels as electromagnetic waves at the speed of light and is absorbed when it strikes matter.

It states that if body A is in thermal equilibrium with body C, and body B is also in thermal equilibrium with body C, then A and B are in thermal equilibrium with each other.

The first law says that the heat supplied to a system is equal to the increase in its internal energy plus the external work it does.

Both of these modes need matter: conduction passes energy from particle to particle and convection carries it by the movement of a fluid.

This is the heat that one gram of water at a hundred degrees Celsius must absorb to become steam at the same temperature, with no rise in temperature at all; the same quantity is released when steam condenses back to water.

Water behaves abnormally between zero and four degrees: it contracts as it is heated in that range and expands again above four degrees, so the same mass occupies its least volume, and therefore has its greatest density, at four degrees Celsius.

Heat is a form of energy in transit, so it is measured in the same unit as work and energy, the joule, which is one newton metre.

In orbit the gravitational pull of the earth is the very force that keeps the craft curving around the planet, and the craft, the astronaut and everything inside accelerate towards the earth at the same rate.