General Science Mixed Quiz: Set 195

Light keeps to a straight line only while its speed stays the same, which happens in a homogeneous, transparent medium.

Velocity ratio is defined as the distance moved by the effort divided by the distance moved by the load in the same interval of time, and because it depends only on the design of the machine it does not change with friction, unlike the mechanical advantage.

With the same voltage, heat varies inversely as resistance, and the parallel resistance is one-fourth of the series resistance. The two wires are identical, so each has the same resistance R. In series the total resistance is R + R = 2R; in parallel it is R/2.

Heavy water is D₂O: two atoms of deuterium joined to one atom of oxygen. Deuterium is the isotope of hydrogen with one proton and one neutron in its nucleus, so it is about twice as heavy as ordinary hydrogen.

The mass of the solution is 20 g + 180 g = 200 g, and 20 g of salt in 200 g of solution is 10 per cent.

When an electric current is passed through brine, a concentrated aqueous solution of sodium chloride, the salt decomposes. Chlorine gas is given off at the anode and hydrogen gas at the cathode, while sodium hydroxide is left in the solution near the cathode.

The blind spot is the place where the optic nerve leaves the eye, and it has no rods or cones, so light falling there is not seen.

In lyophilisation the material is first frozen and then placed under a strong vacuum, so that the ice changes directly into vapour without passing through the liquid state.

Moment of inertia is the sum of each bit of mass multiplied by the square of its distance from the axis, so drawing the arms in reduces it.

The Central Silk Board was constituted under the Central Silk Board Act, 1948 and works under the Ministry of Textiles with its headquarters in Bengaluru, from where it runs the country's sericulture research and seed organisation.

In simple harmonic motion the velocity is given by omega times the square root of A squared minus x squared.

This is the defining condition of simple harmonic motion, written F = −kx, where k is the force constant and the minus sign shows that the force always points back towards the mean position.

Brewster found that when unpolarised light falls on a transparent surface at one particular angle of incidence, called the polarising angle, the reflected light is completely plane polarised, and at that angle the refractive index of the surface equals the tangent of the polarising angle.

A beam seen from the side is visible only because tiny particles send some of its light sideways. Light travelling in a straight line cannot enter our eyes unless something redirects it towards us.

In a short circuit the resistance of the path falls almost to zero, so by Ohm's law the current rises sharply.

Egg white is mostly water and protein, and heat denatures these proteins so that they set into an opaque white solid.

Power is the reciprocal of the focal length in metres, so P = 1 ÷ 0.25 m = +4 D. The power of a lens tells how strongly it converges or diverges light.

Varignon theorem states that the moment of a force about any point equals the algebraic sum of the moments of its components about the same point; it speaks of the moments themselves, not of their squares, so statement S1 is false as written.

A swing is a pendulum, and its speed is greatest at the lowest point, where all the potential energy gained at the top has turned into kinetic energy.

By the Rayleigh criterion the smallest angle the eye can resolve is 1.22 times the wavelength divided by the diameter of the pupil, that is 1.22 multiplied by 500 nanometres and divided by 3 millimetres, which comes to about 2.03 times ten to the power minus four radian.