In an alternating current circuit consisting of elements in series, the current increases on increasing the frequency of supply. Which of the following elements are likely to consitute the circuit ?

Options

A. Only resistor
B. Resistor and inductor
C. Resistor and capacitor
D. Only inductor

Explanation

To solve the problem, we need to analyze how the current in an alternating current (AC) circuit changes with frequency when different circuit elements are present. The key elements to consider are resistors and capacitors.

### Step-by-Step Solution:

1. **Understanding the Circuit Elements**:
- In an AC circuit, the main components are resistors (R), inductors (L), and capacitors (C). Each of these components reacts differently to changes in frequency.

2. **Effect of Frequency on Capacitors**:
- The capacitive reactance (Xc) is given by the formula:
\[ X_c = \frac{1}{2 \pi f C} \]
- Here, \( f \) is the frequency and \( C \) is the capacitance. As the frequency \( f \) increases, the capacitive reactance \( X_c \) decreases.

3. **Current in a Capacitor**:
- The relationship between voltage (V), current (I), and capacitive reactance (Xc) is given by:
\[ I = \frac{V}{X_c} \]
- Since \( X_c \) decreases with an increase in frequency, the current \( I \) will increase as well.

4. **Effect of Frequency on Resistors**:
- In the case of a resistor, the relationship is given by Ohm's law:
\[ V = I R \]
- The resistance \( R \) does not depend on frequency. Therefore, increasing the frequency will not affect the current in a purely resistive circuit.

5. **Combining Resistors and Capacitors**:
- When a resistor and a capacitor are connected in series, the current will be influenced by the capacitor's reactance. As the frequency increases, the reactance decreases, leading to an increase in current.

6. **Conclusion**:
- The circuit that will see an increase in current with an increase in frequency must include a capacitor. Therefore, the likely elements that constitute the circuit are a combination of a resistor and a capacitor.

### Final Answer:
The elements likely to constitute the circuit are a combination of a **resistor and a capacitor**.

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