AdvancedA-001-003-011
What is the value of capacitance (C) in a series R-L-C circuit, if the circuit resonant frequency is 14.25 MHz and L is 2.84 microhenrys?
B
Answer
Advanced theory and components
Type
A
2.2 picofarads
B
44 picofarads
C
44 microfarads
D
2.2 microfarads
Answer Notes
To solve for capacitance when you know the resonant frequency and inductance, you must rearrange the standard resonant frequency formula to: C = 1 / (4π²f²L).
First, convert your knowns to standard units: f = 14.25 × 10^6 Hz and L = 2.84 × 10^-6 henrys. Square the frequency, then multiply by 4π² (approx 39.478) and the inductance.
The denominator becomes approximately 2.276 × 10^10. Dividing 1 by this denominator yields roughly 4.39 × 10^-11 farads, which smoothly converts to 44 picofarads. The microfarad options are incorrect by a factor of one million.
Previous · A-001-003-010
What is the resonant frequency of a series RLC circuit, if R is 47 ohms, L is 1 microhenry and C is 9 picofarads?
Next · A-001-004-001
What is the resonant frequency of a parallel RLC circuit if R is 4.7 kilohms, L is 1 microhenry and C is 10 picofarads?