Question

Which of the following is true regarding their eccentricity "e":
1. Circle: e = 1, Ellipse: e < 1, Parabola: e > 1, Hyperbola: e = 0.
2. Circle: e = 1, Ellipse: e > 1, Parabola: e = 0, Hyperbola: e < 1.
3. Circle: e = 0, Ellipse: e < 1, Parabola: e = 1, Hyperbola: e > 1.
4. Circle: e = 0, Ellipse: e = 1, Parabola: e < 1, Hyperbola: e > 1.

Answer 1

Correct Answer - Option 3 : Circle: e = 0, Ellipse: e < 1, Parabola: e = 1, Hyperbola: e > 1.

Concept:

The eccentricity of a conic section is the ratio of the distance of a point on the curve to its focus and it's the distance to the directrix.

 

Calculation

Eccentricity is a measure of how much a conic section deviates from being circular. In particular:

The eccentricity of a circle is 0.

The eccentricity of an ellipse (which is not a circle) is greater than 0 but less than 1.

The eccentricity of a parabola is 1.

The eccentricity of a hyperbola is greater than 1.