# Ohms Law

1. Feb 7, 2008

### 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?

#### Attached Files:

• ###### OA-Ammeter.bmp
File size:
236.2 KB
Views:
65
Last edited: Feb 7, 2008
2. Feb 8, 2008

### jhicks

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).