Solve the Problem $$e = 20 \sin \left( \frac { \pi t } { 4 } - \frac { \pi } { 2 } \right)$$

question 119

Multiple Choice

Solve the problem.
-A coil of wire rotating in a magnetic field induces a voltage given by
$$e = 20 \sin \left( \frac { \pi t } { 4 } - \frac { \pi } { 2 } \right)$$
where $t$ is time in seconds. Find the smallest positive time to produce a voltage of $10 \sqrt { 2 }$ .

• A) \(3 \mathrm { sec }\)
• B) \(3 \pi \mathrm { sec }\)
• C) \(2.8 \pi \mathrm { sec }\)
• D) \(2.8 \mathrm { sec }\)

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