Physics Electricity

Electricity :

Static electricity :

Static electricity is an imbalance of electric charges within or on the surface of a material or between materials. It is created when two surfaces contact and have worn and separated, and at least one of the surfaces has a high resistance to electric current. Static electricity refers to the accumulation or build-up of electric charge on the surface of an object. When two objects are rubbed together, especially if the objects are insulators and the surrounding air is dry, the objects acquire equal and opposite charges and an attractive force develops between them. The object that loses electrons becomes positively charged, and the other becomes negatively charged. Static electricity is often created when two objects that are not good electrical conductors are rubbed together, and electrons from one of the objects rub off onto the other.

Current resistance and potential difference :

Current is the flow of electric charge. Electric charge ( Amps , connected in series ) will only flow round a fully complete circuit if there's potential difference ( volts , connected in parallel ). Potential difference is the driving force that pushes charge around. Resistance slows the flow down ( ohms ). The current flowing through a component depends on the potential difference across it and the resistance of the component . The greater the resistance across the component , the smaller the current that flows ( for a given potential difference ) the component. The size of current is the rate of flow of charge . When current flows past a point in a circuit fora legth of time then the charge that has passed is given by this formula : Q ( charge flow ) = I ( current ) x T ( time )

Ohm's law :

Current (I) and resistance are related by Ohm’s Law, which states that the current flowing through a conductor is directly proportional to the Potential difference (V) across it and inversely proportional to the resistance. The formula is ( V = I \times R ). Higher resistance means less current for a given voltage. 

Resistance of wire :

The resistance of a circuit can depend on a number of factors, wether the components are in series or parallel or the legth of the wire. steps test 1 :

• attach a crocodile clip to the wire level with 0cm on the ruler
• Attach the second crocodile clipto the wire , write down the legth of the wire between the clips .
• Close the switch ,then record the current through the wire and the potential difference across
• Open the second switch , then move the clip . Close the…