NEET Alternating Currents — Set 16

Question 1

In an AC circuit with a series combination of resistor and capacitor, what determines whether the circuit is predominantly capacitive?

Accepted Answer

In an RC series circuit, the circuit is predominantly capacitive if the capacitive reactance ($ X_C = \frac{1}{\omega C} $) is greater than the resistance ($ R $). This makes the impedance $ Z = \sqrt{R^2 + X_C^2} $ dominated by $ X_C $, and the current leads the voltage significantly.

Question 2

A $ 200 \, \text{V} $ (rms) AC source supplies a $ 100 \, \Omega $ resistor. What is the peak voltage?

Accepted Answer

Peak voltage: $ v_m = \sqrt{2} V $. $ V = 200 \, \text{V} $. $ v_m = 1.414 \times 200 = 282.8 \, \text{V} \approx 283 \, \text{V} $.

Question 3

A transformer has $ N_p = 700 $, $ N_s = 350 $. If $ V_p = 280 \, \text{V} $ (rms), what is the secondary voltage?

Accepted Answer

$ \frac{V_s}{V_p} = \frac{N_s}{N_p} $. $ V_s = V_p \times \frac{N_s}{N_p} = 280 \times \frac{350}{700} = 140 \, \text{V} $.

NEET Physics: Alternating Currents — Practice Set 16

Q1. In an AC circuit with a series combination of resistor and capacitor, what determines whether the circuit is predominantly capacitive?

Q2. A \( 200 \, \text{V} \) (rms) AC source supplies a \( 100 \, \Omega \) resistor. What is the peak voltage?

Q3. A transformer has \( N_p = 700 \), \( N_s = 350 \). If \( V_p = 280 \, \text{V} \) (rms), what is the secondary voltage?

Q4. A series LCR circuit has \( R = 20 \, \Omega \), \( X_L = 30 \, \Omega \), \( X_C = 50 \, \Omega \). What is the power factor?

Q5. In an AC circuit with a series combination of resistor and inductor, what happens to the impedance if the frequency decreases?

Q6. What is the primary energy loss mechanism in a real transformer that reduces its efficiency?

Q7. A \( 130 \, \text{V} \) (rms) AC source supplies a \( 65 \, \Omega \) resistor. What is the average power consumed?

Q8. A series LCR circuit with \( R = 60 \, \Omega \), \( X_L = 80 \, \Omega \), \( X_C = 20 \, \Omega \) has a \( 180 \, \text{V} \) (rms) source. What is the power dissipated?

Q9. A \( 60 \, \Omega \) resistor is connected to a \( 180 \, \text{V} \) (rms) AC source. What is the rms current?

Q10. A series LCR circuit has \( L = 3 \, \text{H} \), \( C = 12 \, \mu\text{F} \). What is the resonant angular frequency?