Q. 57

Expert-verifiedFound in: Page 793

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 .

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

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.

We have given,

Résistance of ammeter =

We have to find the effective resistance of new ammeter.

Since both ammeter and resistance are in parallel.

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