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Q. 57

Expert-verified
Found in: Page 793

### Physics for Scientists and Engineers: A Strategic Approach with Modern Physics

Book edition 4th
Author(s) Randall D. Knight
Pages 1240 pages
ISBN 9780133942651

# A circuit you’re building needs an ammeter that goes from to a full-scale reading of . Unfortunately, the only ammeter in the storeroom goes from to a full-scale reading of only . Fortunately, you’ve just finished a physics class, and you realize that you can make this ammeter work by putting a resistor in parallel with it, as shown in FIGURE P28.57. You’ve measured that the resistance of the ammeter is, not theof an ideal ammeter.a. What value of R must you use so that the meter will go to full scale when the current I is?b. What is the effective resistance of your ammeter?

a. The value of R is .

b. The effective resistance will be .

See the step by step solution

## Part (a) Step 1: Given information

We have given,

We needs ammeter of full scale reading =

We have ammeter of full scale reading =

we have to find the value of R such that we get the full scale reading

## Step 2: Simplify

The total measured current should be

since ammeter has some resistance then voltage drop across the ammeter will be as voltage drop across resistance. since they are parallel.

## Part (b) Step 1: Given information

We have given,

Résistance of ammeter =

We have to find the effective resistance of new ammeter.

## Step 2: Simplify

Since both ammeter and resistance are in parallel.