Heat Transfer Mechanisms

This is the correct answer. The heat budget or the heat balance of the earth is the reason why the earth neither warms up nor cools down despite the huge transfer ofheat that takes place.

This is the correct answer as both a and b statements are incorrect. Plank’s law states that hotter a body, the more energy it will radiate and shorter the wavelength of that radiation. Specific heat is the energy needed to raise the temperature of one gram of substance by one Celsius.

Temperature is an intensive property.

Trade winds are caused by convection currents in the atmosphere. The differential heating between the equator and poles creates convection cells (Hadley cells) where warm air rises at the equator and cooler air descends in the subtropics. The rotation of the Earth (Coriolis effect) deflects these winds, creating the persistent trade wind patterns. Conduction, radiation, and scattering are not the primary mechanisms driving these winds.

A thermos flask prevents heat loss through conduction and convection using vacuum, and through radiation using silver coating on inner walls. The vacuum between the walls stops heat transfer by conduction and convection since both require matter. The silver coating reflects infrared radiation back into the flask, keeping contents hot or cold.

Heat transfer depends on mass (Q = mcΔθ), temperature change, and the specific heat capacity of the substance. Specific heat capacity varies by material, so all three factors affect the amount of heat absorbed or released.

The sun and earth are separated by vacuum (space). Heat cannot be transferred by conduction (requires medium) or convection (requires fluid medium) in vacuum. The only mode of heat transfer possible through vacuum is radiation, which travels as electromagnetic waves (infrared, visible light). Therefore, heat from sun reaches earth by radiation alone.

Electric current generates heat in metallic wires primarily due to collisions between conduction electrons (the charge carriers) and the metal atoms in the wire lattice. As electrons drift through the wire under electric potential, they collide with atoms, transferring kinetic energy to them. This increased atomic vibration manifests as heat - this is Joule heating. Electron-electron collisions don't significantly contribute to heating, and ionization doesn't occur in normal conduction.

Explanation for (1): The only error in the sentence is of adjective usage. A little means some, little means next to nothing, which is the sense applied here.

Heat, sound, and light are all forms of energy that can be transferred or transformed. Heat is thermal energy, sound is mechanical wave energy, and light is electromagnetic energy. The nucleus is a physical part of an atom composed of protons and neutrons, not a form of energy itself. Energy can be stored in nuclear forces within the nucleus, but the nucleus itself is matter.

Yes, it is the correct answer. Upon heating, a non-luminous object becomes a luminous object.

Yes on heating, metal expands in size.

According to Fourier's Law of heat conduction, the rate of heat transfer per unit area (heat flux) is proportional to the temperature gradient (dT/dx). The temperature gradient represents the change in temperature over a distance perpendicular to the area.

Convection is the process of heat transfer in fluids where energy is transported by the physical movement of the fluid's molecules. This differs from conduction, where energy is passed between stationary molecules.