# Dc Circuit theory exam question - reseeds

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7 Οκτ 2013 (πριν από 4 χρόνια και 7 μήνες)

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DC circuit theory exam question

In the ci
rcuit
shown below
the value of the load resistance, R, is chosen so that the
dissipation
is maximised.

a) Derive the Thevenin equivalent of the network to which the
resistance R is

connected.

b
) Calculate the value of R to maximise the load power
dissipation and the value of the

c) With the value of R calculated in part b) connected in the circuit, calculate the power
supplied by each of the sources.

12V

1
A

1

4

R

12

Solution

a) The circuit can be reduced to its Thevenin equivalent using source equivalence and combining
resistances in series and parallel:

b) Required load resistance = 4

r =
E
2
/4R =
(6
*
6
)/(4*4) =

2.25

W

3
3 / 4 = 0.75
A,

so
the electrical conditions in the
remainder of the
circuit are:

So:

Power from 1A source =
3.75

*

1.0 =
3.75
W

Power from
1
2
V

source =
12 * 0.69

=
8
.25

W

12V

1A

1

4

R

12

1

1A

4

R

1A

12

2A

R

6
V

4

R

3

1

0.94A

1

1
A

4

4

0.75A

0.75
V

3V

12V

12

3.75V

1.69A

0.69A