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What is hot molten rock called?
Lava
Magma
Igneous rocks
Volcano
Magma
Quick Summary: Magma is the molten or semi-molten natural material found beneath the Earth's surface. When this substance erupts from a volcano and reaches the surface, it is referred to as lava.
Magma is the molten or semi-molten natural material found beneath the Earth's surface. When this substance erupts from a volcano and reaches the surface, it is referred to as lava.
Q=mcΔT — Heat energy content in geothermal reservoirs
η=1−ThotTcold — Carnot efficiency limit for heat-to-power conversion
Magma is generated in the Earth's mantle or lower crust due to high temperatures and pressures. When the pressure exceeds the structural integrity of the surrounding rock, or due to tectonic movement, it rises toward the crust through vents or fissures. Geothermal energy extraction often utilizes the heat associated with these high-temperature reservoirs, though the molten state itself is rarely directly tapped.
Magma exists below the crust; Lava exists above the crust.
Magma is composed of molten rock, dissolved gases, and suspended crystals.
The transition from magma to lava involves the release of volatiles (gases) due to the drop in lithostatic pressure.
Geothermal power plants utilize the thermal energy derived from magma-heated crustal zones.
High energy density in concentrated magma zones
Provides a baseline power generation capability
Extreme temperatures and corrosive chemical environments
High technological complexity for drilling and material durability
Geothermal Power Generation
District Heating Systems
| Feature | Magma | Lava |
|---|---|---|
Location | Below surface | Above surface |
Igneous rocks are formed by the cooling and solidification of magma or lava.
A volcano is the structural landform or vent through which the material reaches the surface.
Option A is incorrect as it refers to the material only after surface exposure.
Option C is incorrect as it refers to the cooled solid state, not the molten state.
Option D is incorrect as it describes the geological feature/vent, not the material itself.
B is correct — Magma is the technical term for molten rock residing beneath the Earth's lithosphere.
In engineering exams, differentiate clearly between magma (sub-surface) and lava (surface) as they represent different stages of energy potential in geothermal thermodynamic cycles.