The distance between an object and its real image in a co...
The distance between an object and its real image in a convex lens is 40cm. If the magnification of the image is 3, calculate the focal length of the lens
6.5 cm
7.5 cm
8.5 cm
4.5 cm
Correct answer is B
u + v = 40
vu = 3
v = 3u
u + 3u = 40
4u = 40
u = 10cm
v = 3u = 30cm
f = uvu+v=10(30)10+30=30040
= 7.5 cm
Which of the following instruments is best for measuring the diameter of a thin constantan wire? ...
The melting point of a substance is equivalent to its ...
In which of these fields are repulsive forces NOT experienced? I. Magnetic field II. Gravitati...
Which of the following statements about moving particle is correct? ...
Which of the following CANNOT be deflected by both electric and magnetic fields? ...
In measuring high frequency a.c, the instrument used is the ...
Which of the following statements about electrolysis is NOT correct? ...