This question asks about the relationship between the temperature of a conductor and its electrical resistance. We need to recall the microscopic behavior of electrons and atoms in a conductor as temperature changes.
Understanding Resistance: Electrical resistance in a conductor arises from the collisions between free electrons (which constitute the current) and the atoms/ions of the conductor's lattice structure. The more frequent or energetic these collisions, the higher the resistance.
Effect of Temperature Increase: When the temperature of a conductor increases, the thermal energy of its constituent atoms/ions also increases. This increased thermal energy causes the atoms/ions to vibrate with greater amplitude and frequency around their mean positions in the lattice.
Impact on Electron Flow: As the atoms/ions vibrate more vigorously, they present a greater obstacle to the flow of free electrons. The probability of collisions between the drifting electrons and the vibrating atoms/ions increases significantly.
Result on Resistance: More frequent and energetic collisions impede the smooth flow of electrons, thereby increasing the opposition to the current. Consequently, the electrical resistance of the conductor increases.
Mathematical Relation (for most conductors): For many metallic conductors, the resistance \(R_T\) at a temperature \(T\) can be approximated by the formula:
\[ R_T = R_0 [1 + \alpha (T - T_0)] \]
Where:
Since \(\alpha\) is positive for conductors, if \(T > T_0\), then \(R_T > R_0\), meaning resistance increases with temperature.
Correct Option: A) Increases
When the temperature of a conductor increases, the atoms within the conductor vibrate more vigorously, leading to more frequent collisions with the free electrons. These increased collisions impede the flow of electrons, thus increasing the resistance of the conductor.
The question asks to identify the law that describes the relationship between voltage, current, and resistance in an electric circuit. We need to recall the fundamental laws of electricity and their respective applications.
Correct Option: B) Ohm's Law describes the direct relationship between voltage, current, and resistance in an electric circuit, stating \(V = IR\).
This question asks about the actual direction of electron flow in an electric circuit. It's important to distinguish between conventional current direction and the actual electron flow.
B) From negative to positive - Electrons, being negatively charged, are repelled by the negative terminal and attracted to the positive terminal of a voltage source. Thus, they flow from the negative terminal to the positive terminal in the external circuit.
The question asks to identify a conductor of electricity from the given options. A conductor is a material that allows electric current to flow through it easily, typically due to the presence of free electrons. Insulators, on the other hand, resist the flow of electricity.
Correct Option: C) Copper is a metal and possesses free electrons, which allow it to conduct electricity efficiently. It is widely used in electrical wiring and components for this very reason.
The question asks for the SI unit of electric charge. This requires recalling the fundamental SI units for various electrical quantities.
Correct Option: C) Coulomb
The question describes a scenario where two materials are rubbed together, causing electrons to transfer from one to the other. This process leads to an imbalance of charge on the surfaces of the materials. We need to identify the phenomenon that results from this charge imbalance.
C) Static electricity is the accumulation of electric charge on an insulated body. When two materials are rubbed together, electrons are transferred, creating a charge imbalance (one becomes positively charged, the other negatively charged). This accumulated, non-flowing charge is static electricity.