Current Electricity

1. Electromotive Force (emf)

1.1. SI Unit :

1.1.1. V (Volts)

1.2. Definition :

1.3. Formula :

1.3.1. E = W/Q

1.4. Measured with :

1.4.1. Voltmeter connected parallel to source

1.5. Has the same unit as potential difference(p.d.)

2. Potential Difference(p.d.)

2.1. Definition:the amount of energy when one coulomb of positive charge passes between the two points

2.2. V=W/Q

2.3. SI Unit: volt(V)

2.4. Measure with a voltmeter parallel to the component of the circuit

3. Resistance

3.1. definition:the ratio of potential difference across the conductor and the current flowing in it.

3.2. formula:R=V/I (units:ohm)

3.3. masurement

3.3.1. In series: R=R1+R2

3.3.2. In parallel: 1/R=1/R1+1/R2

3.4. fixed resistors &viable resistor(rheostat)

4. Current

4.1. Caused by :

4.1.1. flow of electrons around a complete circuit

4.2. Electron flow opposite to conventional current flow

4.3. Electron flow :

4.3.1. moves from negative terminal of source to positive terminal

4.4. Measured with :

4.4.1. Ammeter

4.5. Formula :

4.5.1. I = Q/t

4.6. Definition :

4.6.1. Rate of flow of charges