Class 12 Physics

Question 7.1:

Solution 7.1: (b)

NCERT Exemplar Textbook: CBSE Class 12 Physics – All Chapters

Question 7.2:

An alternating current generator has an internal resistance R_g and an internal reactance X_g. It is used to supply power to a passive load consisting of a resistance R_g and a reactance X_L. For maximum power to be delivered from the generator to the load, the value of X_L is equal to

(a) zero

(b) X_g

(c) -X_g

(d) R_g

Solution 7.2: (c)

In order to deliver maximum power the generator to the load, the total reactance must be equal to zero, i.e., X_L + X_g = 0 Þ X_L = ‒ X_g.

Question 7.3:

Solution 7.3: (c)

Question 7.4:

To reduce the resonant frequency in an L-C-R series circuit with a generator

(a) the generator frequency should be reduced

(b) another capacitor should be added in parallel to the first

(c) the iron core of the inductor should be removed

(d) dielectric in the capacitor should be removed

Solution 7.4: (b)

Question 7.5:

Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication?

(a) R = 20W, L = 1.5H, C = 35mF

(b) R = 25W, L = 2.5H, C = 45mF

(c) R = 15W, L = 3.5H, C = 30 mF

(d) R = 25W, L = 1.5H, C = 45mF

Solution 7.5: (c)

Question 7.6:

An inductor of reactance 1W and a resistor of 2W are connected in series to the terminals of a 6V (rms) AC source. The power dissipated in the circuit is

(a) 8W

(b) 12W

(c) 14.4W

(d) 18W

Solution 7.6: (c)

Question 7.7:

Solution 7.7: