Reactance and impedance — NEET & JEE Questions

Question 1 · difficulty L1 · recall

Inductive reactance is

• A. XL=1/(ωL)
• B. XL=ωC
• C. XL=ωL
• D. XL=R/ω

Question 2 · difficulty L1 · understanding

Capacitive reactance is

• A. XC=ωC
• B. XC=ωL
• C. XC=Rω
• D. XC=1/(ωC)

Question 3 · difficulty L2 · understanding

The SI unit of reactance is

• A. ohm
• B. henry
• C. farad
• D. tesla

Question 4 · difficulty L2 · application

As AC frequency increases, inductive reactance

• A. decreases
• B. increases
• C. remains constant
• D. becomes negative resistance

Question 5 · difficulty L2 · understanding

When the frequency of an AC source is increased, which of the following happens to the inductive reactance $X_L$ and the capacitive reactance $X_C$?

• A. $X_L$ decreases and $X_C$ increases
• B. Both increase
• C. $X_L$ increases and $X_C$ decreases
• D. Both decrease

Question 6 · difficulty L3 · application

As AC frequency increases, capacitive reactance

• A. increases
• B. remains constant
• C. decreases
• D. becomes equal to capacitance

Question 7 · difficulty L3 · application

For a series RLC circuit, impedance magnitude is

• A. R+XL+XC
• B. sqrt(R²+XL²+XC²) always
• C. XL-XC without R
• D. sqrt(R²+(XL-XC)²)

Question 8 · difficulty L3 · application

An inductor of inductance $\frac{1}{\pi}$ H is connected to a 50 Hz AC supply. Its reactance is

• A. 50 $\Omega$
• B. 314 $\Omega$
• C. 25 $\Omega$
• D. 100 $\Omega$

Question 9 · difficulty L3 · application

A resistor of 30 $\Omega$ and an inductor of reactance 40 $\Omega$ are connected in series to a 200 V (rms) AC source. The impedance of the circuit and the rms current are

• A. 50 $\Omega$ and 4 A
• B. 70 $\Omega$ and 2.86 A
• C. 10 $\Omega$ and 20 A
• D. 35 $\Omega$ and 5.7 A

Question 10 · difficulty L4 · analysis

A pure inductor is connected to AC. Current relative to voltage

• A. lags by 90°
• B. leads by 90°
• C. is always in phase
• D. lags by 180°