Electric current is measured by :

Options

A. Resistance
B. Voltmeter
C. Capacitor
D. Ammeter

Explanation

To answer the question "Electric current is measured by:", we can follow these steps:

### Step 1: Understand the Measurement of Electric Current
Electric current is the flow of electric charge in a circuit. To measure this flow, we need a specific instrument designed for this purpose.

### Step 2: Identify the Correct Instrument
Among the options provided (resistance, voltmeter, capacitor, and emitter), we need to identify which instrument is specifically used to measure electric current.

### Step 3: Recognize the Function of Each Instrument
- **Resistance**: This measures how much a material opposes the flow of electric current but does not measure current itself.
- **Voltmeter**: This measures the voltage (potential difference) across two points in a circuit, not the current.
- **Capacitor**: This stores electrical energy but does not measure current.
- **Ammeter**: This is the instrument specifically designed to measure electric current.

### Step 4: Conclusion
The correct instrument to measure electric current is the **ammeter**. It is connected in series with the circuit to measure the current flowing through it.

### Final Answer
Electric current is measured by an **ammeter**.

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