Revision  notes  Ohm’s  Law:    

         Resistors  in  series  

 Same  current  through  all  the  resistors  but  different  voltages  across  individual  resistors.    

Resistors  in  parallel  

   

Total  resistance  RT  RT = R1 + R2 + R3 =10+ 20+30 = 60Ω  

 

Total  resistance  RT  1RT

=1R1+1R2+1R3=110

+120

+130

= 0.1+ 0.05+ 0.0333= 0.1833

⇒ RT =1

0.1833= 5.46Ω

 

 Total  Voltage  No  need  to  calculate.    Total  voltage    =  10V    

Total  and  individual  Voltages  No  need  to  calculate.    Voltage  across  each  resistor  =  10V  

Total  and  individual  Currents  

I = VSRT

=1060

= 0.167A  

Total  current  

I = VSRT

=105.46

=1.83A  

Individual  voltages  

 V1 = IR1 = 0.167x10 =1.67VV2 = IR2 = 0.167x20 = 3.33VV3 = IR3 = 0.167x30 = 5V

 

 

Individual  currents  

   

   

VV

II RR

Vs=10VVs=10V

R1=10ohmR1=10ohm

R2=20ohmR2=20ohm

R3=30ohmR3=30ohm

II

R1=10ohmR1=10ohm

R2=20ohmR2=20ohm

R3=30ohmR3=30ohm

Vs=10VVs=10V

II

Vs=10VVs=10V

II

RRTT

Vs=10VVs=10V

II

RRTT

Vs=10VVs=10V

R1=10ohmR1=10ohm

R2=20ohmR2=20ohm

R3=30ohmR3=30ohm

II

V1V1 V2V2V3V3

R1=10ohmR1=10ohm

R2=20ohmR2=20ohm

R3=30ohmR3=30ohm

Vs=10VVs=10V

II

I1I1

I2I2

I3I3

 

Same  voltage  across  the  resistors  but  different  currents  through  individual  resistors.