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Category: Class 12 Physics

NCERT Solutions for Class 12 Physics updated for CBSE academic session 2021-2022.

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

Do the same exercise as above with the replacement of the earlier transformer by a 40,000-220 V step-down transformer (Neglect, as before, leakage losses though this may not be a good assumption any longer because of the very high voltage transmission involved). Hence, explain why high voltage transmission is preferred?

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.26 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 26

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

Obtain the resonant frequency and Q-factor of a series LCR circuit with L = 3.0 H, C = 27 μF, and R = 7.4 Ωμ. It is desired to improve the sharpness of the resonance of the circuit by reducing its ‘fiill width at half maximum’ by a factor of 2. Suggest a suitable way.

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.21 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 21

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

A power transmission line feeds input power at 2300 V to a stepdown transformer with its primary windings having 4000 turns. What should be the number of turns in the secondary in order to get output power at 230 V?

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.23 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 23

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

At a hydroelectric power plant, the water pressure head is at a height of 300 m and the water flow available is 100 m³ s⁻¹. If the turbine generator efficiency is 60%, estimate the electric power available from the plant (g = 9.8 ms⁻²).

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.24 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 24

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

A small town with a demand of 800 kW of electric power at 220 V is situated 15 km away from an electric plant generating power at 440 V. The resistance of the two wire line carrying power is 0.5 Ω. per km. The town gets power from the line through a 4000220 V step-down transformer at a sub-station in the town. (a) Estimate the line power loss in the form of heat. (b) How much power must the plant supply, assuming there is negligible power loss due to leakage? (c) Characterise the step up transformer at the plant.

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.25 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 25

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

Answer the following questions: (a) In any ac circuit, is the applied instantaneous voltage equal to the algebraic sum of the instantaneous voltages across the series elements of the circuit? Is the same true for rms voltage? (b) A capacitor is used in the primary circuit of an induction coil. (c) An applied voltage signal consists of a superposition of a dc voltage and an ac voltage of high frequency. The circuit consists of an inductor and a capacitor in series. Show that the dc signal will appear across C and the ac signal across L. (d) A choke coil in series with a lamp is connected to a dc line. The lamp is seen to shine brightly. Insertion of an iron core in the choke causes no change in the lamp’s brightness. Predict the corresponding observations if the connection is to an ac line. (e) Why is choke coil needed in the use of fluorescent tubes with ac mains? Why can we not use an ordinary resistor instead of the choke coil?

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.22 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 22

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

A series LCR circuit with L = 0.12 H, C = 480 nF, R = 23 Ω is connected to a 230 V variable frequency supply. (a) What is the source frequency for which current amplitude is maximum? Obtain this maximum value. (b) What is the source frequency for which average power absorbed by the circuit is maximum? Obtain die value of this maximum power. (c) For which frequencies of the source is the power transferred to the circuit half the power at resonant frequency? What is the current amplitude at these frequencies? (d) What is the Q-factor of the given circuit?

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.20 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 20

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

A 100 Ω resistor is connected to a 220 V, 50 Hz ac supply. (a) What is the rms value of current in the circuit? (b) What is the net power consumed over a full cycle?

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.1 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 1

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

Suppose the initial charge on the capacitor in Exercise 7.7 is 6 mC. What is the total energy stored in the circuit initially? What is the total energy at later time?

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.8 NCERT Solutions for Class 12 Physics Chapter 7 Question 8

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

A charged 30μF capacitor is connected to a 27 mH inductor. What is the angular frequency of free oscillations of the circuit?

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.7 NCERT Solutions for Class 12 Physics Chapter 7 Question 7

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Category: Class 12 Physics

Obtain the resonant frequency and Q-factor of a series LCR circuit with L = 3.0 H, C = 27 μF, and R = 7.4 Ωμ. It is desired to improve the sharpness of the resonance of the circuit by reducing its ‘fiill width at half maximum’ by a factor of 2. Suggest a suitable way.

A power transmission line feeds input power at 2300 V to a stepdown transformer with its primary windings having 4000 turns. What should be the number of turns in the secondary in order to get output power at 230 V?

At a hydroelectric power plant, the water pressure head is at a height of 300 m and the water flow available is 100 m³ s⁻¹. If the turbine generator efficiency is 60%, estimate the electric power available from the plant (g = 9.8 ms⁻²).

A 100 Ω resistor is connected to a 220 V, 50 Hz ac supply. (a) What is the rms value of current in the circuit? (b) What is the net power consumed over a full cycle?

Suppose the initial charge on the capacitor in Exercise 7.7 is 6 mC. What is the total energy stored in the circuit initially? What is the total energy at later time?

A charged 30μF capacitor is connected to a 27 mH inductor. What is the angular frequency of free oscillations of the circuit?

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Category: Class 12 Physics

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