General Science Mixed Quiz: Set 201

Faraday's law is a law of magnitude, not a direction rule. It states that the emf induced in a circuit is proportional to the rate at which the magnetic flux through it changes.

The British geneticist Alec Jeffreys developed DNA fingerprinting in 1984 by studying short repeated sequences that vary in number from person to person, and the method is now used in criminal investigation, in disputes about parentage and in identifying victims of accidents and disasters.

. A simple astronomical (refracting) telescope uses two convex, that is convergent, lenses.

It appears brightest because it is both luminous and close, about 8.6 light years away, and it is in fact a binary system with a white dwarf companion.

Of the four, X-rays lie farthest towards the short-wavelength, high-energy end of the electromagnetic spectrum. All electromagnetic waves travel at the speed of light in vacuum but differ in wavelength.

Raman announced in 1928 that light scattered by a transparent medium contains components of changed wavelength, a shift that reveals the energy levels of the scattering molecules, and the Nobel Prize in Physics followed in 1930, making him the first Asian to receive a Nobel in a science.

Pearls are harvested from pearl oysters, which are bivalve molluscs. When a foreign particle, such as a grain of sand or a parasite, gets inside the shell, the oyster's mantle covers it layer after layer with nacre, the shiny material also called mother of pearl.

When an electric discharge is passed through neon at low pressure it glows a bright reddish orange, which is why the tubes of advertising signs and warning lights are filled with it, and the name neon sign has stuck to such tubes whatever gas they now contain.

The Dutch scientist Huygens designed the first working pendulum clock in 1656, after Galileo had noticed that a swinging lamp took the same time for each swing whether it swung far or little, the property called isochronism.

Tooth enamel is made mainly of calcium phosphate in the form of a hard crystal called hydroxyapatite. Enamel is the hardest substance in the human body, harder even than bone.

Diffraction, the bending of a wave round an edge, is appreciable only when the obstacle or opening is of the same order of size as the wavelength.

Turmeric is Curcuma longa, a rhizome of the ginger family whose yellow colour comes from curcumin, and it is well known in the intellectual property story in which a United States patent on the use of turmeric for wound healing was revoked after India produced evidence of traditional knowledge.

If the frequency of the soldiers' rhythmic steps happens to match the natural frequency of the bridge, the bridge is driven at its own frequency and its amplitude of vibration can build up to a dangerous level; breaking step destroys the rhythm and avoids the risk.

Mycology is the study of fungi, the group that includes moulds, yeasts, mushrooms and the rusts and smuts that attack crops, and a specialist in it is called a mycologist.

The smallest angular separation a telescope can resolve is 1.22 times the wavelength divided by the diameter of the objective, so a larger aperture means a smaller limit of resolution and a greater resolving power.

In a wheelbarrow the wheel acts as the fulcrum, the load sits in the tray between the wheel and the hands, and the effort is applied at the handles, which is the arrangement of a second class lever; because the effort arm is always longer than the load arm, its…

The time period of a simple pendulum depends on its length but not on the mass of the bob, so halving the length divides the period by √2.

Polarisation means restricting the vibrations of a wave to one plane, which is only possible if the vibrations are perpendicular to the direction of travel.

The time period of a simple pendulum depends on the square root of its length and not on its mass, so four times the length gives twice the period.

Thomas Young passed light from one source through two narrow slits placed close together and obtained alternate bright and dark bands on a screen.