A capacitor and an inductor are connected to A.C. supply. If we double the frequency of A.C. supply then the effect on reactance of capacitor XC and reactance of inductor XL will be:
Correct answer: D. XL is doubled and XC reduces to half
- A. Both XC and XL are doubled
- B. Both XC and XL are halved
- C. XC is doubled and XL reduces to half
- D. XL is doubled and XC reduces to half
- E. Both XC and XL are unchanged
Explanation
The reactance of a capacitor is given by: Xc = 1/ (2πfC) where f is the frequency of the AC supply, and C is the capacitance of the capacitor. On doubling the frequency of the AC supply, the reactance of the capacitor becomes: X'c = 1/ (2π(2f)C) = Xc/2 Therefore, the reactance of the capacitor is halved when the frequency is doubled. The reactance of an inductor is given by: XL = 2πfL where L is the inductance of the inductor. On doubling the frequency of the AC supply, the reactance of the inductor becomes: X'L = 2π(2f)L = 2XL Therefore, the reactance of the inductor is doubled when the frequency is doubled.
Last updated
About AC Through Resistor, Capacitor and Inductor
Alternating current through a resistor, capacitor and inductor involves phase relationships between voltage and current, reactance, impedance and energy transfer. A resistor keeps voltage and current in phase, while a capacitor and inductor produce opposite phase shifts, a distinction used in circuit diagrams and numerical calculations.
Practise Alternating Current
592 free Alternating Current MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 15 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
A 10Ω electric heater is connected to a 220V 50Hz mains supply. What is the peak value of the potential difference across the heater element ?
A 220 V main supply is connected to a resistance of 100 k ohms. The effective current is
A 50-m coil carries a current of 2 amperes. The energy stored in a magnetic field is:
A.C. and D.C. have the same __________?
A.C and D.C have the same: