The transistor generator and active resistance
Answers are for parents and teachers.
1
Iₘ = 8 A and Uₘ = 20 V (active resistance). What is the mean power in W?
80
2
The active resistance is 55 Ω on the 220 V (effective) mains. What is the effective current in A?
4
3
What is the power of this heater in W?
880
4
i = 3cos(314t) A. State the current amplitude and the approximate frequency.
Iₘ = 3 A; ν = ω/(2π) ≈ 314/6.28 = 50 Hz
5
Why are effective values rather than amplitudes used when calculating the power of alternating current?
Because the current reaches its peak only for instants; the effective value is the equivalent that gives the same heat as direct current.