JAMB - Physics (1988 - No. 23)
To obtain a magnification of 2.5, how far should an object be placed from the pole of a thin converging lens of focal length 10.20m?
0.13m
0.25m
0.28m
0.50m
คำอธิบาย
v = 2.5u
F = \(\frac {uv}{u + v}\)
0.2 = \(\frac {u \times 2.5u}{u + 2.5u}\)
u = 0.28m
F = \(\frac {uv}{u + v}\)
0.2 = \(\frac {u \times 2.5u}{u + 2.5u}\)
u = 0.28m