Question

A quantitative relationship between the energy absorbed and energy emitted by a body was forward by (a) Einstein (b) Kirchhoff (c) Hess (d) Fermi

Short answer

(b) Kirchhoff

Step-by-step solution

Understand the Question

The question is asking who proposed a quantitative relationship between the energy absorbed and energy emitted by a body. This is related to the principle of energy conservation in physics.

Recall the Information

Know that Albert Einstein is famous for the theory of relativity. Gustav Kirchhoff is known for his laws on electrical circuits. Germain Hess introduced the concept of Hess's law in thermochemistry, and Enrico Fermi is recognized for his work on beta decay. Based on the context of the question, we can eliminate Einstein, Kirchhoff, and Fermi.

Final Answer

Considering the options and recalling the contributions of these scientists, the answer is (b) Kirchhoff because he proposed the law of thermal radiation, which is a quantitative relationship between the energy absorbed and energy emitted by a body.

Key concepts

Understanding Quantitative Relationships in Physics

In physics, a quantitative relationship is a mathematical expression that describes how different quantities are related.
More specifically, it provides a way to measure and predict how one quantity affects another. For example, consider Kirchhoff's Law of Thermal Radiation.
This law gives us a quantitative relationship by defining the proportionality between the energy absorbed and the energy emitted by a body.

• Quantitative relationships help scientists understand the intricacies of physical phenomena.
• They often take the form of equations or formulas.
• These relationships are crucial for developing theories and models of the natural world.

Kirchhoff's Law is essential as it allows us to quantify the balance of energy in thermodynamic systems.
Without quantitative relationships, it would be difficult to predict outcomes or design systems that rely on specific physical principles.

Energy Conservation in Physics

The principle of energy conservation states that energy cannot be created or destroyed; it can only change forms.
This principle is fundamental in physics and ensures the energy balance within any closed system remains constant over time.

• In every process, the total energy of a system remains the same.
• Energy can transition between kinetic, potential, thermal, and other forms.
• This principle helps in solving various physics problems, from mechanics to thermodynamics.

When we apply this to Kirchhoff's Law, we see how energy absorbed by a body has to be balanced by the energy it emits.
This concept is vital in understanding not just thermal radiation, but also electrical circuits, and chemical reactions.
Energy conservation is a backbone of many physical theories and is necessary for the technological advancements we see in our modern world.

Exploring Thermal Radiation

Thermal radiation is the process by which energy is emitted by a body due to its temperature.
It is a type of electromagnetic radiation that includes visible light, infrared, and ultraviolet rays.

• All bodies emit thermal radiation as long as their temperature is above absolute zero.
• The energy emitted increases with temperature.
• This phenomenon is described by laws such as Planck's Law and Kirchhoff's Law.

Kirchhoff's contribution was vital because it provided a way to understand thermal radiation's role in energy exchange.
His law states that a good absorber is a good emitter, meaning a body that absorbs more radiation will also emit more.
This understanding is crucial in fields like astronomy, where analyzing the spectrum of celestial objects helps determine their temperature and composition.