Practice MCQ Questions and answers on Physics-GK

The combined gas law allows you to derive any of the relationships needed by combining all of the changeable pieces in the ideal gas law: namely pressure, temperature and volume.

The primary agent of contact metamorphism is temperature.

The resistance of metallic conductors e.g, platinum, increases with rise of temperature . The increase in temperature results in a decrease of current which can be recorded in a galvanometer if the conductor is included in an electrical circuit. Thus the temperature can be known; platinum resistance thermometer is used generally for accurate scientific work. When two dissimilar metals are joined at the ends, and these ends are subjected to a difference of temperature, a current flows through the metals. Greater the difference of temperature , greater the current. So the curent strength can form the basis for measuring the difference in temperature. And when one of these temperatures is known, we can calculate the other.

Anything in a tight skin or shell can explode in a microwave because the water inside can expand and burst through. It is for this very reason that before microwaving, the skin of potatoes should be pricked, winter squash and similar vegetables should be cut in half, eggs should be taken out of shells and holes should be poked in the plastic wrap or sealed pouches of frozen packaged foods.

When two ice cubes are pressed together, they join to form one cube due to hydrogen bond.

Real gases approximate ideal gases when their pressure is relatively low, and their temperature reasonably high. A real gas deviates increasingly from ideality as it is compressed and cooled to near the point at which it will condense into a liquid. Compressing forces the molecules closer together so that intermolecular forces become stronger, and cooling reduces the kinetic energy of the molecules, so that they are more easily held by these forces.

A hygrometer is an instrument used to measure relative humidity. Humidity is the measure of the amount of moisture in the air. A psychrometer is an example of a hygrometer.

When a metal plate with a circular hole at its centre is heated, definitely along with the areal expansion of the plate the diameter of the circular hole also increases. Using the differential equations of coefficients of expansions, we find that the hole radius increases at the same linear rate as the metal.

The value of coefficient of restitution in perfectly elastic collision is 1.

Pyrometer is best suited for measuring the temperature inside metallurgical furnaces.