Question

Column I gives some devices and Column II gives some processes on which the functioning of these devices depend. Match the devices in Column I with the processes in Column II and indicate your answer by darkening appropriate bubbles in the \(4 \times 4\) matrix given in the ORS. Column I \(\quad\) Column II (A) Bimetallic strip (p) Radiation from a hot body (B) Steam engine (q) Energy conversion (C) Incandescent lamp (r) Melting (D) Electric fuse (s) Thermal expansion of solids

Short answer

(A) - (s) Thermal expansion of solids, (B) - (q) Energy conversion, (C) - (p) Radiation from a hot body, (D) - (r) Melting.

Step-by-step solution

Match Device A - Bimetallic strip

Identify the process associated with a bimetallic strip. Bimetallic strips function based on the difference in thermal expansion rates of two metals. When these metals are heated, they expand at different rates, which causes the strip to bend. The correct process for the bimetallic strip is therefore thermal expansion of solids.

Match Device B - Steam engine

Determine the process on which a steam engine operates. A steam engine works by converting the thermal energy from steam into mechanical work. This transformation involves an energy conversion from heat to mechanical energy. Therefore, we associate the steam engine with energy conversion.

Match Device C - Incandescent lamp

Find the process related to an incandescent lamp. The basic principle behind an incandescent lamp is the emission of light from a hot body due to its temperature. When electrical current passes through the filament, it gets hot and radiates light. So, radiation from a hot body is the process that matches the incandescent lamp.

Match Device D - Electric fuse

Identify the working process of an electric fuse. An electric fuse works as a safety device to protect electrical circuits from excess current. It has a metallic wire that melts when a high current passes through, breaking the circuit. The correct match for an electric fuse is melting.

Finalizing Results

Now that all devices have been matched with their respective processes, fill in the appropriate bubbles in the matrix on the ORS to indicate the answers: (A) with (s), (B) with (q), (C) with (p), and (D) with (r).

Key concepts

Thermal Expansion of Solids

Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature. When it comes to solids, this is usually due to the increase in vibration and movement of the atoms or molecules within the material as they absorb heat. Different materials have varying coefficients of thermal expansion, which measures how much a material expands per unit length for each degree of temperature increase.

In practical applications, such as in a bimetallic strip, this concept is critical. A bimetallic strip consists of two metals with different expansion rates bonded together. As temperature changes, one metal expands or contracts more than the other, leading to the strip bending or curving. This movement can then be utilized to trigger mechanical movements or switch devices on or off as a result of the changing temperature.

Energy Conversion

Energy conversion is the process of changing one form of energy into another. This is an essential concept in physics, as energy can neither be created nor destroyed, but can be transformed from one form to another. This principle is known as the conservation of energy.

In the context of a steam engine, for instance, the energy stored in steam, which is thermal energy, is converted into mechanical energy. The steam engine operates by using high-pressure steam produced from boiling water to drive a piston back and forth. This reciprocating motion is then used to do work, such as turning wheels or driving mechanical equipment. This conversion of energy is fundamental to many machines and is the backbone of various engines and power generating systems.

Radiation from a Hot Body

Radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. All objects emit thermal radiation as a result of their temperature.

The incandescent lamp is a classic example of thermal radiation from a hot body. Inside the lamp, the filament is heated by electric current to a high temperature until it glows and emits light. The spectrum of light emitted depends on the filament's temperature, resulting in visible light and some infrared radiation. This process, known as incandescence, is a visible form of thermal radiation and illustrates the broader concept of electromagnetic radiation emitted by hot objects.

Melting Process

The melting process is the transition of a substance from its solid phase to its liquid phase. At the melting point, the solid and liquid phase exist in equilibrium, and adding heat causes the solid to convert into a liquid. This phase change occurs because the molecules in a solid gain enough thermal energy to overcome the forces holding them in rigid structures.

An electric fuse is a safety device that incorporates the melting process as its pivotal operating principle. It contains a metal wire which melts when too much current flows through it. The melting of the wire breaks the circuit, which prevents damage from overheating by interrupting the excessive current flow. This protective measure effectively uses the melting process as a triggering mechanism for the safety of electrical systems.