If a parabolic reflector is 20 cm in diameter and 5 cm deep, find the focus.

Options

A. (0,5)
B. (5,0)
C. (0,4)
D. (4,0)

Answer

B

Explanation

Let POQ be the parabolic reflector which is 20 cm in diameter and 5cm deep. `
` then, Pq=20cm and Or=5cm, where R is the mid- point of Pq. We take Ox as x-axis and Oy as Y-axis the equation of parabola may be taken as y^(2) = 4ax since, thwe point P (5,10) lies on the parabola. `rArr` therefore`, the cooridate of the focus are (a,0)i.e.(5,0). hence, the focus is the given diameter. `