A Cross-Section of a Parabolic Reflector Is Shown in the Figure

question 52

Multiple Choice

A cross-section of a parabolic reflector is shown in the figure. The bulb is located at the focus and the opening at the focus is $18 \mathrm {~cm}$ . Find an equation of the parabola. Let $V$ be the origin. Find the diameter of the opening $| C D | , 19 \mathrm {~cm}$ from the vertex.

• A) \(| C D | = 6 \sqrt { 38 }\)
• B) \(| C D | = 18\)
• C) The equation is \(y = 18 x ^ { 2 }\)
• D) \(| C D | = 4 \sqrt { 414 }\)
• E) The equation is \(y ^ { 2 } = 18 x\)
• F) The equation is \(y ^ { 2 } - \frac { x ^ { 2 } } { 18 } = 1\)

---

Definitions:

Hold-in Windings

Windings in an electromagnetic device that maintain a magnetic field to keep a component, such as a relay or solenoid, in an activated state.

Cool Down Period

Cool down period refers to the time allowed for a machine, engine, or system to gradually return to ambient temperature after operation, to avoid stress or damage from abrupt temperature changes.

Cranking Time

The duration required to rotate an engine's crankshaft to start the engine.

Voltage Loss

The decrease in electrical potential within a circuit, usually resulting from the resistance or impedance present in its components.