To determine the SI unit of specific heat capacity, we need to recall its definition and the formula associated with it. Specific heat capacity is defined as the amount of heat energy required to raise the temperature of a unit mass of a substance by one degree Kelvin (or Celsius).
Recall the formula for heat transfer: The amount of heat energy (\(Q\)) absorbed or released by a substance is given by the formula:
\[ Q = mc\Delta T \]
where:
Rearrange the formula to solve for specific heat capacity (\(c\)):
\[ c = \frac{Q}{m\Delta T} \]
Substitute the SI units for each variable:
Combine the units to find the unit of \(c\):
\[ \text{Unit of } c = \frac{\text{Unit of } Q}{\text{Unit of } m \times \text{Unit of } \Delta T} = \frac{\text{J}}{\text{kg} \cdot \text{K}} \]
Thus, the SI unit of specific heat capacity is Joules per kilogram Kelvin (J/kg·K).
Correct Option: B) J/kg·K
The question asks to identify the process of heat transfer through a fluid. We need to recall the definitions of different heat transfer mechanisms: conduction, convection, radiation, and insulation.
B) Convection is the process by which heat is transferred through a fluid (liquid or gas) by the actual movement of the fluid itself. As the fluid is heated, it becomes less dense and rises, while cooler, denser fluid sinks, creating a continuous circulation that transfers thermal energy.
The question asks to identify a good conductor of heat from the given options. Heat conduction is the transfer of thermal energy through direct contact. Materials that allow heat to pass through them easily are called good conductors, while those that resist heat transfer are called insulators.
C) Copper — Copper is a metal and is known for its excellent thermal conductivity. This is due to the presence of free electrons in its atomic structure, which can readily absorb and transfer thermal energy throughout the material. It is widely used in electrical wiring, cooking utensils, and heat exchangers for this very reason.
The heat transfer that does not require a medium is
The question asks to identify the mode of heat transfer that does not require a material medium for its propagation. We need to recall the definitions and characteristics of the three primary modes of heat transfer: conduction, convection, and radiation.
Correct Option: C) Radiation — Radiation is the transfer of heat in the form of electromagnetic waves. These waves can travel through a vacuum, meaning no material medium is required for heat to be transferred by radiation. The heat from the sun reaching Earth is a prime example of heat transfer by radiation.
The question asks for the primary cause of global warming. We need to evaluate each option based on its role in the Earth's climate system and its contribution to the observed increase in global temperatures.
B) Greenhouse gases — An increase in greenhouse gases (such as carbon dioxide, methane, and nitrous oxide) in the atmosphere, primarily from human activities like burning fossil fuels, traps more heat, leading to an enhanced greenhouse effect and global warming.
The question asks about the cause of the greenhouse effect. We need to identify the primary mechanism by which certain atmospheric gases trap heat, leading to the warming of the Earth's surface and lower atmosphere.
A) Absorption and emission of infrared radiation by the atmosphere
This option accurately describes the fundamental mechanism of the greenhouse effect. Greenhouse gases in the atmosphere absorb the infrared radiation emitted by the Earth's surface and then re-emit it in all directions, including back towards the Earth's surface, thereby trapping heat.