In the DC bridge circuit shown in Fig. 6.22, the resistive components have the following values: R1 ¼ R2 ¼ 120 U ; R3 ¼ 117 U ; R4 ¼ 123 U ; and Ra ¼ Rp ¼ 1000 U. (a) What are the resistance values of...

In the DC bridge circuit shown in Fig. 6.22, the resistive components have the

following values: R1 ¼ R2 ¼ 120 U ; R3 ¼ 117 U ; R4 ¼ 123 U ; and

Ra ¼ Rp ¼ 1000 U.

(a) What are the resistance values of the parts of the potentiometer track on either

side of the slider when the potentiometer is adjusted to balance the bridge?

(b) What then is the effective resistance of each of the two left-hand arms of the

bridge when the bridge is balanced?

[Note: This question will involve the solution of a quadratic equation. For a

quadratic equation of the form: ax2 þ bx þ c ¼ 0, the solution is given by

x ¼ b ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

b2 4ac p

2a

].