Which unit is used to measure Noise ?
A. Decibel
B. Hertz
C. Ohm
D. Volt

Options

A. A
B. B
C. D
D. C

Answer

To solve the question "Which unit is used to measure Noise?", we will analyze each option provided:

1. **Decibel (dB)**: This is a unit used to measure the intensity of sound, which includes noise. It quantifies sound levels in a logarithmic scale.

2. **Hertz (Hz)**: This unit measures frequency, which is the number of cycles per second of a periodic phenomenon. It is not used to measure noise directly.

3. **Ohm (Ω)**: This is the unit of electrical resistance. It does not relate to sound or noise measurement.

4. **Volt (V)**: This unit measures electric potential difference. It is also not related to measuring noise.

Now, since we are looking for the unit that specifically measures noise, the correct answer is **Decibel (A)**.

### Step-by-Step Solution:
1. Identify the question: "Which unit is used to measure Noise?"
2. Review the options provided: Decibel, Hertz, Ohm, Volt.
3. Analyze each option:
- Decibel: Used for measuring sound intensity.
- Hertz: Measures frequency, not noise.
- Ohm: Measures electrical resistance, not related to noise.
- Volt: Measures electric potential difference, not related to noise.
4. Conclude that the correct answer is **Decibel** (A).