The curve showing correct variation of capacitative reactance X_C  with frequency f is:

CONCEPT:

• Reactance: It is basically the inertia against the motion of the electrons in an electrical circuit.

• There are two types of reactance:

  1. Capacitive reactance (X_C) (Ohms is the unit)

  2. Inductive reactance (X_L) (Ohms is the unit)

EXPLANATION:

VARIATIONS OF DIFFERENT QUANTITIES WITH FREQUENCY

The variations of reactance with frequency are shown in Fig

Variation of inductive reactance X_L

• The inductive reactance X_L (= 2πfL) is directly proportional to the frequency f, hence its graph is a straight line through the origin.

Variation of capacitive reactance X_C

• The capacitive reactance X_C [= 1/(2πfC)] is inversely proportional to the frequency, hence its graph is a rectangular hyperbola. X_L versus f and X_C versus f curves cut at a point where f = f₀

Variation of net reactance X

• The graph of net reactance x (= X_L - X_C) is obtained from X_L versus f and -X_C versus f curves. It is a hyperbola (but not a rectangular hyperbola). This curve crosses the frequency axis at a point where f = f₀.