Related InterviewSolutions

• A capacitor 'C', a variable resistor 'R' and a bulb 'B' are connected in series to the ac mains in circuit as shown. The bulb glows with some brightness. How will the glow of the bulb change if (i) a dielectric slab is introduced between tie plates of the capacitor, keeping resistance R to be the same; (ii) the resistance R is increased keeping the same capacitance ?
• A device ‘X’ is connected to an a.c source. The variation of voltage, current and power in one complete cycle is shown in Fig 7.5. (a) Which curve shows power consumption over a full cycle? (b) What is the average power consumption over a cycle? (c) Identify the device ‘X’.
• A device 'X' is connected to an a.c. source V = V0 sin tot. The variation of voltage, current and power in one complete cycle is shown in the following figure.(i) Which curve shows power consumption over a full cycle?(ii) Identify the device'X'.
• For an ideal conductor, connected across a sinusoidal ac voltage source. State which one of the following quantity is zero :(i) Instantaneous power(ii) Average power over full cycle of the ac voltage source.
• The frequency of a.c. source is doubled. How do R, XL and Xc get affected?
• 1. The peak voltage of an ac supply is 300V. What is the rms voltage?2. The rms value of current in an ac circuit is 10A. What is the peak current?
• Calculate resistance peak voltage and rms current in a 100 W bulb connected to 220 V supply. 
• Mention of expression for instantaneous, peak and rms values of alternating current and voltage.
• For L-R circuit, the time constant is equal to(A) Twice the ratio of the energy stored in the magnetic field to the rate of dissipation of energy in the resistance. (B) Ratio of the energy stored in the magnetic field to the rate of dissipation of energy in the resistance. (C) Half the ratio of the energy stored in the magnetic field to the rate of dissipation of energy in the resistance. (D) Square of the ratio of the energy stored in the magnetic field to the rate of dissipation of energy in the resistance.
• The ratio of time constant in build-up and decay in the circuit shown in figure is(A) 1:1 (B) 3:2 (C) 2:3 (D) 1:3