Electrical Power Quiz 1Graded A+

What is the relationship between electric charge and electric current? - ANSWER-Electric current is the rate of movement of electrical charges. A flow of electrons occurs when a battery and conductors form a closed loop. Where do these electrons come from? - ANSWER-They are always present in the conductor as free electrons. What is the essential difference between conductors and insulators? - ANSWER-Conductors allow the free passage of current and insulators don't and are extremely poor conductors. What is the function of electrical insulation? - ANSWER-Electrical insulators function to offer high opposition to the passage of current between two or more conductors How do conductors used for energy transmission differ from those used for limiting current? Give examples of each. - ANSWER-They have good electrical conductivity (little opposition to current). Whereas the latter has low conductivity conductors. -Buses for energy transmission (copper) -Resistors for limiting current (iron) Explain why the passage of current through a conductor generates heat. - ANSWER-When electrons are driven through a metallic conductor, they collide with some of the atoms that make up the material and generate heat. What effect does increasing temperature have on (a) copper; (b) Manganin; (C) carbon? - ANSWER-a; increased resistance b; almost not affected or very small amount c; decreased resistance Define ampacity and state the factors that affect it - ANSWER-The current in amperes that a conductor can carry continuously without exceeding the temperature rating of its insulation. Factors affecting it: Thermal stability of the insulation, the heat dissipation capability, the number of conductors in the cable or pipe, duty cycle. Define resistivity; - ANSWER-The resistance of a specified length and cross section of that material. Define resistance; - ANSWER-Property of a material that limits the current and converts electrical energy into thermal energy.