Question

A wire-wound `resistive potentiometer type' angle sensor with 72 turns is used. The first turn is connected to ground and the last turn to 3.6 V. The wiper width covers two turns ensuring make-before-break. The output (wiper) voltage when the wiper is on top of both turns 35 and 36 is _____(rounded off to two decimal places).

Hint:

For wire-wound pots, when the wiper bridges two adjacent turns, the output is the \textbf{average} of the two tap voltages.

Answer 1

Correct Answer: 1.77

Total turns $=72$ from $0$ to $3.6\,$V $\Rightarrow$ voltage per turn $=\dfrac{3.6}{72}=0.05\,$V.
Turn 35 potential $V_{35}=35\times0.05=1.75\,$V; turn 36 potential $V_{36}=36\times0.05=1.80\,$V.
With make-before-break, the wiper bridges turns 35 and 36, so the output equals the average: \[ V_o=\frac{V_{35}+V_{36}}{2}=\frac{1.75+1.80}{2}=1.775\text{ V}\approx \boxed{1.78\text{ V}}. \]