# How much current (in A) flows through the ammeter for Circuit b?

• kapopka88
In summary, the ammeter is used in series with the load, and the combined resistance of the circuit is 0.1 ohm plus the resistance of the headlight. The manufacturer specifies a current of 6A for the headlight, but it should actually be slightly less due to the headlight's resistance of 2 ohm.
kapopka88
The manufacturer of a 12V car headlight specifies it will draw a current of 6A. You would like to check this claim with an ammeter designed to measure currents up to 10A and having a resistance of 0.1 Ohms. Which of the two figures below represents a circuit where the ammeter correctly measures the current in the headlight?
OA-Ammeter.bmp

a. Circuit a.
b. Circuit b.

How much current (in A) would flow in the ammeter for Circuit a?

i thought A would equal V/R, which in this case i thought would be 12/.1= 120 amps... but this is not correct. please help!

How much current (in A) flows through the ammeter for Circuit b?

#### Attachments

• OA-Ammeter.bmp
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The pictures haven't authenticated yet, but ammeters are used in series with the load (headlight) so that the combined resistance of the circuit is 0.1ohm + the resistance of the headlight which is supposedly 12V/6A = 2ohm. If the headlight truly is 2ohm, you should see slightly less current than 6A with the ammeter hooked up (it's your job to find how much though).

For Circuit b, the current flowing through the ammeter can be calculated using Ohm's law: I = V/R, where I is the current, V is the voltage, and R is the resistance.

In this case, the voltage (V) is 12V and the resistance (R) is 0.1 Ohms. Therefore, the current flowing through the ammeter for Circuit b would be:

I = 12V / 0.1 Ohms = 120 amps

This means that the ammeter would correctly measure the current in the headlight, since the manufacturer specified it would draw a current of 6A and the ammeter is capable of measuring currents up to 10A. The figure for Circuit b is the correct one.

For Circuit a, the current flowing through the ammeter would be:

I = 12V / 0.1 Ohms = 120 amps

This is also correct, but it does not match the manufacturer's specification of 6A for the headlight. Therefore, the figure for Circuit b is the correct one for measuring the current in the headlight.

## 1. What is an ammeter and what does it measure?

An ammeter is a device used to measure the amount of electric current flowing through a circuit. It is typically connected in series with the circuit and measures the current in units of amperes (A).

## 2. What is the significance of measuring current in a circuit?

Measuring current is important because it helps us understand the flow of electricity in a circuit. It allows us to determine if the circuit is functioning properly and to identify any potential issues or faults.

## 3. How is the ammeter connected in Circuit b?

In Circuit b, the ammeter is connected in series with the other components. This means that the current flows through the ammeter before reaching the other components in the circuit.

## 4. Can the ammeter measure both AC and DC current?

It depends on the type of ammeter. Some ammeters are designed to measure only AC current, while others can measure both AC and DC current. It is important to check the specifications of the ammeter to ensure it is suitable for the type of current being measured.

## 5. What factors affect the reading on the ammeter for Circuit b?

The reading on the ammeter for Circuit b can be affected by the resistance of the components in the circuit, as well as the voltage of the power source. Additionally, the accuracy of the ammeter itself can also impact the reading.

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