A designer wishes to use a simple modification of the circuit of Fig 2.20 on page 86 of the Text to implement a centre-zero voltmeter whose scale ends are Il volt. The meter movement provided is a 0 to I mA unit with a resistance of 50 U. Her boss suggests that a solution is possible using a single additional resistor and one of the ±10 V supplies from which the op amp is powered. What is the value of the additional resistor? To what supply is it connected? To what circuit node is the additional resistor connected? What is the required value of R?