Physics NCERT Exemplar Solutions Class 11th Chapter Fifteen

A 5 V battery is connected across the points X and Y. Assume D₁ and D₂ to the normal silicon diodes. Find the current supplies by the battery if the +ve terminal of the battery is connected to point X.

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A : When a rod lying freely is heated, no thermal stress is developed in it.

Reason R : On heating, the length of the rod increases.

In the light of the above statements, choose the correct answer from the options given below:

The pitch of the screw gauge is 1mm and there are 100 divisions on the circular scale. When nothing is put in between the jaws, the zero of the circular scale lies 8 divisions below the reference line. When a wire is placed between the jaws, the first linear scale division is clearly visible while 72^nd division on circular scale coincides with the reference line, The radius of the wire is:

Given below are two statements:

Statement I : A speech signal of 2 kHz is used to modulate a carrier signal of 1 MHz. The bandwidth.

Statement II :  The side band frequencies are 1002 kHz and 998 kHz.

In the light of the above statements, choose the correct answer from the options given below:

Which of the following statements are true for a stationary wave?

(a) Every particle has a fixed amplitude which is different from the amplitude of its nearest particle.

(b) All the particles cross their mean position at the same time.

(c) All the particles are oscillating with same amplitude.

(d) There is no net transfer of energy across any plane.

(e) There are some particles which are always at rest.

A train, standing in a station yard, blows a whistle of frequency 400 Hz in still air. The wind starts blowing in the direction from the yard to the station with a speed of 10m/s. Given that the speed of sound in still air is 340m/s,

(a) The frequency of sound as heard by an observer standing on the platform is 400Hz.

(b) The speed of sound for the observer standing on the platform is 350m/s.

(c) The frequency of sound as heard by the observer standing on the platform will increase.

(d) The frequency of sound as heard by the observer standing on the platform will decrease.

The transverse displacement of a string (clamped at its both ends) is given by y (x,t) = 0.06 sin (2πx/3) cos (120πt). All the points on the string between two consecutive nodes vibrate with

(a) Same frequency

(b) Same phase

(c) Same energy

(d) Different amplitude.

During propagation of a plane progressive mechanical wave

(a) All the particles are vibrating in the same phase.

(b) Amplitude of all the particles is equal.

(c) Particles of the medium executes S.H.M.

(d) Wave velocity depends upon the nature of the medium.

Speed of sound waves in a fluid depends upon

(a) Directly on density of the medium.

(b) Square of Bulk modulus of the medium.

(c) Inversely on the square root of density.

(d) Directly on the square root of bulk modulus of the medium.

The displacement of a string is given by y(x,t) = 0.06 sin (2πx/3) cos (120πt) where x and y are in m and t in s. The length of the string is 1.5m and its mass is 3.0* ${10}^{-2}\mathit{k}\mathit{g}$  .

(a) It represents a progressive wave of frequency 60Hz.

(b) It represents a stationary wave of frequency 60Hz.

(c) It is the result of superposition of two waves of wavelength 3 m, frequency 60Hz each travelling with a speed of 180 m/s in opposite direction.

(d) Amplitude of this wave is constant.