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ELECTRIC CURRENT

Physics

CURRENT ELECTRICITY

Electric potential difference and electric current Electric current: Electric potential difference (p. d) is defined as the work done per unit charge in moving charge from one point to another. It is measured in volts. Electric current is the rate of flow of charge. P. d is measured using a voltmeter while current is measured using an ammeter. The SI units for charge is amperes (A).   Ammeters and voltmeters In a circuit an ammeter is always connected in series with the battery while a voltmeter is always connected parallel to the device whose voltage is being measured.   Ohm’s law This law gives the relationship between the voltage across a conductor and the current flowing through it. Ohm’s law states that “the current flowing through a metal conductor is directly proportional to the potential difference across the ends of the wire provided that temperature and other physical conditions remain… Read More »CURRENT ELECTRICITY

Physics

MAGNETIC EFFECT OF AN ELECTRIC CURRENT

Introduction: Oersted’s discovery. Hans Christian Oersted discovered the magnetic effect of a current in 1819. The direction of the field is dependent on the direction of the current. This discovery brought about the development of electric bells, electric motors, telephone receivers and radios.   Determining the direction of the lines of force. The direction of the lines of force can be determined using a simple rule called the right-hand screw rule. This rule states that “if a right-hand screw advances in the direction of the current , then the rotation of the screw is in the direction of the field”.   Another rule is the right-hand grip rule which states that “if the wire carrying a current is gripped with the right hand, using the thumb along the conductor and pointing in the direction of the current, then the direction of curled fingers is in the direction of the lines… Read More »MAGNETIC EFFECT OF AN ELECTRIC CURRENT

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