B5

• potential difference


  the work done per unit charge in moving the charge from one point to another
• conductors


  materials with many free electrons per unit volume, through which thermal energy and electric current can pass easily
• insulators


  materials with few free electrons per unit volume, through which thermal energy and electric current cannot readily pass
• direct current


  rate of flow of charge through the cross-sectional area of a conductor
• electrical resistance


  the ratio of voltage across conductor to the current through it
• Ohm's law


  at a constant temperature, the current through a metallic conductor is proportional to the voltage across the conductor
• thermistor


  temperature-dependent resistor where resistance decreases as temperature increases
• light dependent resistor


  resistor where resistance decreases as light intensity increase
• resistivity


  the resistance of a conductor of unit length and unit cross-sectional area
• voltage


  the potential difference across a conductor
• electric power


  the energy per unit time dissipated in a conductor
• internal resistance


  a resistance in series to the cell due to the chemicals in the cell
• electromotive force (emf)


  the work done per unit charge in moving charge across a battery's terminals
• parallel connection


  resistors connected one after the other so they take the same current
• ammeter


  an instrument that measures the electric current through it
• voltmeter


  an instrument that measures the potential difference across its ends
• ideal voltmeter


  a voltmeter with infinite resistance connected to a resistor
• Kirchhoff's first law


  the total current flowing into a junction equals the total current flowing out of the junction
• Kirchhoff's second law


  the sum of the IR products in any closed loop is equal to the emf supplied in that loop