2015 - WAEC Physics Past Questions and Answers - page 3
Which of the following concepts is a method of heat transfer that does not require a material medium?
Which of the following units is the S.I. unit of heat capacity?
Heat capacity = \(\frac{\text{Heat energy supplied}}{\text{Rise in temperature}}\)
= JK\(^{-1}\)
Users' Answers & CommentsAn object is placed 15cm from a diverging lens of focal length 12cm. The image of the object formed by the lens in
The focal length of a diverging lens is negative.
f = -12 cm; u = 15 cm.
\(f = \frac{uv}{u + v}\)
\(-12 = \frac{15v}{15 + v}\)
\(-12 (15 + v) = 15v \implies -180 - 12v = 15v\)
\(-180 = 15v + 12v \implies -180 = 27v\)
\(v = \frac{-180}{27} = -6.67 cm\)
The image is virtual and 6.67 cm from the lens.
Users' Answers & Commentsn = (\frac{\text{real depth}}{\text{apparent depth}})
1.3 = (\frac{2.1}{\text{apparent}})
A.D = (\frac{2.1}{1.3} = 1.6)
V = (\frac{2nx}{E})
= (\frac{2 \times 1 \times X}{0.8} = 320)
2x = 0.8 x 320
x = (\frac{0.8 \times 320}{2})
= 128m