Question

A circuit you're building needs an ammeter that Part A goes from 0 mA to a full-scale reading of 70.0 mA Unfortunately, the only ammeter in the storeroom goes from 0μA to a full-scale reading of only 500μA. Fortunately, youve just finished a physics What value of R must you use so that the meter will go to full scale when the current I is 70.0 class, and you realize that you can make this ammeter work by putting a resistor in parallel with it, as shown in the figure (Fgure 1). Youve measured that the resistance of the ammeter is 20.0Ω, not the 0Ω of an ideal ammeter. Part B What is the effective resistance of your ammeter? Express your answer in ohms.

Answer 1

To make the ammeter work with a full-scale reading of 70.0 mA, a resistor needs to be placed in parallel with it. The formula to calculate the value of the resistor is (Rh * 70) / (500 - 70), where Rh is the resistance of the ammeter.

Step-by-step explanation:

To make the ammeter work with a full-scale reading of 70.0 mA, a resistor needs to be placed in parallel with it. The resistance of the ammeter is given as 20.0Ω. Let's call the resistance of the parallel resistor R. To calculate the value of R, we can use the formula:

R = (Rh * 70.0) / (500 - 70.0)

Where Rh is the resistance of the ammeter. Plugging in the values, we get:

R = (20.0Ω * 70.0) / (500μA - 70.0mA)

This gives us the value of R in ohms, which will allow the ammeter to have a full-scale reading of 70.0 mA.