D.C theory

D.C theory

1. ohms law

   • R = resistance
     • resistors in series
       • Rt = R1 +R2 + R3..
     • resistors in parallel circuit
       • 1/Rt = 1/R1 + 1/R2 + 1/R3
   • v = voltage
     • V=IR
   • I = current
     • opposition to current flow

2. Atoms

   • made up of eletcrons, protons and neutrons
     • electrons are negatively charged (-)
       • electron flow
         • e- (- to +)
       • conventional flow
         • e- (+ to -)
     • protons are possitively charged (+)

3. kirchoff's law

   • the sum of the voltages around the circuit should equal to the total voltage (in series)
     • the current stays the same through out the circuit
   • the current is shared in a parallel circuit
     • the voltage stays the same through out the circuit

4. electromagnetic induction

   • - electrochemistry - photoelectric -thermo electric - piezo electric

5. effects of an electric current

   • thermal - chemical - magnetic - resistance

6. fuse BS1362

   • cartrige magnetic

7. plug top BS1363

   • cord grip - cpc is the last cable to come out from the plug

8. power

   • rate of work over time
   • P = VI P= V2/R P= I2R
   • power is measured in watts

9. prefix

   • (-)
     • milli -m - 10*-3 micro = µ - 10*-6 nano - n - 10*-9 pico - p 10*-12
   • (+)
     • kilo - K - 10*3 mega - M -10*6 giga - G -10*9 terra - T - 10*12

10. resistivity

    • R=pl/A
      • R=resistance p=resitivty l=length A=area