Class 12 Physics

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

A coil of inductance 0.50 H and resistance 100 Ω is connected to a 240 V, 50 Hz ac supply. (a) What is the maximum current in the coil? (b) What is the time lag between the voltage maximum and the current maximum?

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.13 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 13

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

An LC circuit contains a 20 mH inductor and a 50 μF capacitor with an initial charge of 10 mC. The resistance of the circuit is negligible. Let the instant the circuit is closed be t = 0. (a) What is the total energy stored initially? Is it conserved during LC oscillations? (b) What is the natural frequency of the circuit? (c) At what time is the energy stored (i) completely electrical (i.e., stored in the capacitor)? (ii) completely magnetic (i.e., stored in the inductor)? (d) At what times is the total energy shared equally between the inductor and the capacitor? (e) If a resistor is inserted in the circuit, how much energy is eventually dissipated as heat?

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.12 NCERT Solutions for Class 12 Physics Chapter 7 Question 12

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

Figure 7.21 shows a series LCR circuit connected to a variable frequency 230 V source. L = 5.0 H, C = 80μF, R = 40 Ω (a) Determine the source frequency which drives the circuit in resonance. (b) Obtain the impedance of the circuit and the amplitude of current at e ^ the resonating frequency. (c) Determine the rms potential drops across the three elements of the circuit. Show that the potential drop across the LC combination is zero at the resonating frequency.

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.11 NCERT Solutions for Class 12 Physics Chapter 7 Question 11

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

Keeping the source frequency equal to the resonating frequency of the series LCR circuit, if the three elements, L, C and R are arranged in parallel, show that the total current in the parallel LCR circuit is minimum at this frequency. Obtain the current rms value in each branch of the circuit for the elements and source specified in Exercise 7.11 for this frequency.

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.17 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 17

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

Obtain the answers to (a) and (b) in Exercise 7.15 if the circuit is connected to a 110 V, 12 kHz supply? Hence, explain the statement that a capacitor is a conductor at very high frequencies. Compare this behaviour with that of a capacitor in a dc circuit after the steady state.

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.16 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 16

Ashok0210

Asked: March 5, 2021In: Class 12 Physics

A 100 μF capacitor in series with a 40 Ω resistance is connected to a 110 V, 60 Hz supply. (a) What is the maximum current in the circuit? (b) What is the time lag between the current maximum and the voltage maximum?

Class 12 Physics CBSE and UP Board Alternating Current Chapter-7 Exercise 7.15 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 7 Question 15

Ashok0210

Asked: March 4, 2021In: Class 12 Physics

(a) Obtain an expression for the mutual inductance between a long straight wire and a square loop of side a as shown in Fig. 6.21. (b) Now assume that the straight wire carries a current of 50 A and the loop is moved to the right with a constant velocity, v = 10 m/s. Calculate the induced emf in the loop at the instant when x = 0.2 m. Take a = 0.1 m and assume that the loop has a large resistance.

Class 12 Physics CBSE and UP Board Electromagnetic Induction Chapter-6 Exercise 6.16 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 6 Question 16

Ashok0210

Asked: March 4, 2021In: Class 12 Physics

An air-cored solenoid with length 30 cm, area of cross-section 25 cm² and number of turns 500, carries a current of 2.5 A. The current is suddenly switched off in a brief time of 10⁻³s. How much is the average back emf induced across the ends of the open switch in the circuit? Ignore the variation in magnetic field near the ends of the solenoid.

Class 12 Physics CBSE and UP Board Electromagnetic Induction Chapter-6 Exercise 6.15 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 6 Question 15

Ashok0210

Asked: March 4, 2021In: Class 12 Physics

Figure 6.20 shows a metal rod PQ resting on the smooth rails AB and positioned between the poles of a permanent magnet. The rails, the rod, and the magnetic field are in three mutual perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod = 15 cm, B = 0.50 T, resistance of the closed loop containing the rod = 9.0 mil. Assume the field to be uniform. (a) Suppose K is open and the rod is moved with a speed of 12 cm s_1 in the direction shown. Give the polarity and magnitude of the induced emf.(b) Is there an excess charge built up at the ends of the rods when K is open? What if K is closed? (c) With K open and the rod moving uniformly, there is no net force on the electrons in the rod PQ even though they do experience magnetic force due to the motion of the rod. Explain. (d) What is the retarding force on the rod when K is closed? (e) How much power is required (by an external agent) to keep the rod moving at the same speed (=12 cm s_1) when K is closed? How much power is required when K is open? (f) How much power is dissipated as heat in the closed circuit? What is the source of this power? (g) What is the induced emf in the moving rod if the magnetic field is parallel to the rails instead of being perpendicular?

Class 12 Physics CBSE and UP Board Electromagnetic Induction Chapter-6 Exercise 6.14 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 6 Question 14

Ashok0210

Asked: March 4, 2021In: Class 12 Physics

It is desired to measure the magnitude of field between the poles of a powerful loud speaker magnet. A small flat search coil of area 2 cm² with 25 closely wound turns, is positioned normal to the field direction, and then quickly snatched out of the field region. Equivalently, one can give it a quick 90° turn to bring its plane parallel to the field direction). The total charge flown in the coil (measured by a ballistic galvanometer connected to coil) is 7.5 mC. The combined resistance of the coil and the galvanometer is 0.50 Ω . Estimate the field strength of magnet.

Class 12 Physics CBSE and UP Board Electromagnetic Induction Chapter-6 Exercise 6.13 Additional Exercise NCERT Solutions for Class 12 Physics Chapter 6 Question 13

Category: Class 12 Physics

A coil of inductance 0.50 H and resistance 100 Ω is connected to a 240 V, 50 Hz ac supply. (a) What is the maximum current in the coil? (b) What is the time lag between the voltage maximum and the current maximum?

Obtain the answers to (a) and (b) in Exercise 7.15 if the circuit is connected to a 110 V, 12 kHz supply? Hence, explain the statement that a capacitor is a conductor at very high frequencies. Compare this behaviour with that of a capacitor in a dc circuit after the steady state.

A 100 μF capacitor in series with a 40 Ω resistance is connected to a 110 V, 60 Hz supply. (a) What is the maximum current in the circuit? (b) What is the time lag between the current maximum and the voltage maximum?

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