(3)
Use
P
=
I
2
R
to determine the power P dissipated when :
(a)
I
=
9 amps
and
R
=
4
Ω
(b)
I
=
14 amps
and
R
=
5
Ω
(4)
If resistors
R
1
and
R
2
are in parallel
:
1
R
R
1
R
1
R
T
1
2
T
=
+
=
I
then
?
R
T
=
?
(5)
The formula for converting degrees Celcius to degrees Fahrenheit is :
F
9C
5
32
=
+
Convert the following degrees C to degrees F
(a) 10
(b) 100
(c) 20
(d) 0
(6)
The impedance Z in a circuit is given by the formula :
Z
=
R
X
2
c
2
+
where X
c
is the reactance and R is the resistance
Find Z when
(a)
R
=
3
and
X
c
=
4
Ω
(b)
R
=
5
and
X
c
=
12
Ω
(c)
R
=
8
and
X
c
=
15
Ω
(d)
R
=
24 and
X
c
=
7
Ω
Answers on page 38
R
3
R
2
R
1
Unit 1 - An Introduction to Mathematics
© SECTT 2005
Page 25