Unit 5: Electrical and electronic design
LO1: Be able to apply AC and DC circuit theory to
circuit design – DC networks
Learner activity sheet
DC networks are an interconnection of components and voltage sources. They can be analysed using a
number of techniques. These include determining series and parallel resistance combinations, using
Ohm’s Law and using Kirchhoff’s voltage and current laws.
On the following pages are some problems to solve.
March 2015
Activity 1
Look at the DC network below:
R2=3
R1=1
R3=6
R5=4
R4=16
I
20 V
Calculate:
1. Total circuit resistance
2. Current (I) flowing in the circuit if the applied voltage is 20V as shown.
Activity 2
Here is another DC network.
I1
R2=3
R1=1
R4=4
I2
I
March 2015
R =3
3
10 V
R5=6
Calculate:
1. The total resistance of the circuit.
2. The total circuit current (I).
3. Currents I1 and I2 [Hint: the current divides at the first node in the circuit – use Kirchhoff’s current
law to determine how the current divides – or use the current division rule].
4. The voltage drop (potential difference, PD) across each resistor in the circuit – and whether for
this circuit Kirchhoff’s voltage law is satisfied.
March 2015