Ex 6)  Series Circuit

a) Find the 'equivalent resistance'

 

 

RT = R1 + R2

 

 

= 2.0 Ω + 1.0 Ω

 

= 3.0 ohms

 

 

 

 

b) Find the current (IT) going through this circuit

 

VT = ITRT

 

12. Volt = IT(3.0 ohms)

 

IT = 4.0 amps

 

 

 

 

c) Find potential drop across R1 & R2

 

V = IR

V1=4.0 amps(2.0 ohms)

= 8.0 Volts

 

 

V2 =4.0 amps(1.0 ohms)

= 4.0 Volts

 

 

 

 

 

 

Ex 7)

a) Find combined resistance (RT)

 

VT = IT RT

 

= 60. volts/10. amps

 

= 6.0 ohms

 

 

 

b) Find the current in R1

 

V1 = I1R1

 

60. Volts = I120. ohms

 

I1 = 3.0 amps

 

 

c) Find I3

 

V3 = VT = 60. volts

 

Use Ohm's Law

 

V3 = I3R3

 

60. volts = I330. ohms

 

I3  = 2.0 amps

 

 

d) Find R2

 

e) Find value of the second resistor

 

 


 

In a Series Circuit:
 (or anytime current in resistors are equal)

 Potential difference (V)
 across a resistor
 is proportional to resistance

 

V = I R

 

Ex 8)

If the voltage drop across the 3 ohms resistor is 4 volts then the voltage drop across the 6 ohm resistor is

 

3.0 ohms : 4.0 volts

 

6.0 ohms : x

 

x = 8.0 volts

 

 

a) Find the total voltage in this series circuit

 

VT = V1 + V2

 

VT = 8.0 V + 4.0 V

 

= 12 V

 

 

b) Find combined resistance in this circuit

 

RT = 6.0 ohms + 3.0 ohms

 

 

RT = 9.0 ohms

 

 


 

 

c) Total current in this circuit?

VT = ITRT

 

 12 V = IT(9.0 ohms)

 

IT  = 1.3 Amps

 

 

 

 

 

Ex 9)

a) Compare the current through each resistor

 

 

Same (Series Circuit)

 

IT = I1 = I2 = ... 

 


 

 

 

b) Current in this circuit?

 

VT = ITRT 

 

60. V =  IT(30. ohms)

 

IT  = 2.0 Amps

 

 

 

 

 

c) Potential difference in 20 ohm resistor?

 

 

V = IR

 

= 2.0 amps(20. ohms)

 

= 40. V

 

 

 

 

 

Ex 10) Find R2

August Sampler

 

V = IR

 

First Find RT

 

8 V = 1 A(RT)

 

RT  = 8 ohms

 

 

 

 

 

 

 

Find R2

 

RT = R1 + R2

Since

RT  = 8 ohms

 

R = 6 ohms