Isaac Physics Ammeter Sensitivity Question Help

An ammeter has resistance R A =20Ω and can give a maximum current reading of 100mA. To increase the current the ammeter can measure, it can be placed in parallel with a resistor, known as a shunt resistor, as shown in the figure below. What value of R is needed in order for the ammeter to be able to measure an I in up to 5.0A?
pls help. thx

Reply 1

mosaurlodon

if 100mA goes to ammeter, how much current goes to resistor? (total current is 5A)

they both have the same V, as they are parallel, so setting up V=IR for each of them, will let you solve for R.