2015 - WAEC Physics Past Questions and Answers - page 4

\(\frac{1}{U} + \frac{1}{V} = \frac{1}{F}\)

\(\frac{1}{V} = \frac{1}{F} - \frac{1}{U}\)

\(\frac{1}{V} = \frac{1}{15} - \frac{1}{20}\)

\(\frac{1}{V} = \frac{\text{4 - 3}}{60}\)


\(\frac{1}{V} = \frac{1}{60}\)

V = 60cm

M = \(\frac{V}{U} = \frac{60}{20}\)

M = 3.0cm

V_o = V(_{rms}) x (\sqrt{2})

V_o = 6 x 1.414

V_o = 8.484

= 8.5v

Power - IV

I = \(\frac{P}{V}\)

= \(\frac{12000}{2000}\)

I = 6A

Power loss = I\(^2\)R = 6\(^2\) x 20

= 720 W

R = (\frac{PL}{A})

C = (\frac{RA}{P})

C = (\frac{0.60 \times 10^{-6} \times 3}{7.2 \times 10^{-7}})

C = 2.50m