transistor circuits

Darlington pair

Resistance of the LDR and the resisitor should be similar so that there isn't a massive voltage difference.

Bigger the resisitance the less steep the line on a graph I/V

Parallel circuit

The voltmeter showed 6 volts which was the same number of volts as the battery pack. This proves that the voltage is the same anywhere on a parallel circuit.

I1 = Vin/Rtot 

18/09/13 Formula

P = VI     Unit [j/s]

P = E/T

V = E/Q  Unit [V or j/c] 

I = Q/T Unit [c/s or A]

1/Rtot = 1/R1 + 1/R2 + ...


P - Power (unit W)

V- Volts

E - Energy

I - Current  (unit A)

Q - Coulons (unit C) 

J - Joules

T - Time (unit s for seconds)

When you add things in parallel, the resistance lowers and the current increases. 

 

 

1) Resistance = 475 kilo ohms

     Current = 0.0955 A

     Total Volts = 6V

     Volt = 3.50 V

 

     Power = 3.50V* 0.0955A = 0.33425W

 

2) Resistance = 442 ohms

    Current = 0.114 A

    Total Volt = 6V

     Volt = 3.52 V

 

Power = 3.52V * 0.114A = 0.40228W



 

 

 

 

 

 

 

 

Digital Multimeter

1.  Confirm voltage divider theory practice.

I connected a 470 ohms and 10k ohms resistor and I got a reading of 5.68V.
The total volts was 6V.










2. Connect Ammeter and state current R(tot) = V(0)/I



1.47Kohms = 6/0.1



 

Power and Current


1 Watt is 1 Joule
I = V/R

P = VI

1. What is the current through a 60W bulb?
    
    60 = 230 * I
    I = 6/23A


   
 

Lesson 1

1. What are the voltages?

a) V1 = 10/110 *9= 9/11

    V2 = 100/110 * 9= 90/11

b) V1 = 30/66 * 10 = 100/33

    V2 = 36/66 * 10 = 60/11

c)  V1 = 2/9 * 10 = 10/9

     V2 = 3/9 * 10 = 10/3

      V3 = 4/9 * 10 = 40/9