Physics full notes of class 11 ch7
The correct answers with their questions numbers.
1 = C , 2 = B , 3 = C , 4 = D , 5 = B , 6 = D , 7 = D , 8 = A , 9 = A , 10 = C , 11 = C , 12 = A
Physics full notes of class 11 ch7 Mcqs End.
Question 1 Answer: Microwave oven: The microwave oven is an important application of resonance. In microwave oven , the microwave with a frequency similar to the natural frequency of vibrations of water molecules or fat molecules of the food are used. When food is placed in the oven , the water molecules and fat molecules of food resonates. As a result , these molecules absorbs energy from microwaves and consequently the food gets heated up.
Radio Reciever: Tuning of radio is another important application of resonance. When we turn the knob of a radio to tune a station , we are changing the frequency of the electrical circuit of the reciever to make it equal to the transmission frequency of radio station. When the two frequencies match each other maximum absorption of energy takes place and thus we hear the concern station very clearly.
Question 4 Answer: Free Oscillation: When a system oscillate with its own natural frequency and no net forces acts on it then such oscillation of the system is known as free oscillation.
Example: When a simple pendulum is displaced from its mean position and then left free it execute from oscillations.
Forced Oscillation: When a system oscillate under the influence of a net external force then such oscillation is known as forced oscillation.
Example: If the mass of a vibrating pendulum is struck again and again then such oscillations of the pendulum is called forced oscillations.
The vibrations of a factory floor caused by the running of heavy machinery is another example of forced oscillations.
Question 5 Answer: When a simple pendulum is set into vibrations and left untouched then with the passage of time its amplitude decreases due to air resistance. The energy of oscillating system is utilized against air resistance due to which damped oscillations are produced. The amplitude of oscillations decreases gradually and finally the pendulum stops its mean position.
Question 8 Answer: We know that the frequency of a simple pendulum is given by, f = 1/2pie underroot g/e
Equation shows that the frequency of simple pendulum depends upon the length of the pendulum. It does not depend on the amplitude of vibrations.
Question 9 Answer: Yes, a singer holding a note of right frequency can shatter a glass due to resonance phenomenon. Every solid body has a certain natural frequency of vibration. If a singer holds a note of a particular frequency equal to the natural frequency of the glass, then resonance occurs and amplitude of vibrations of the glass atoms (molecules) will increase more and more. As a result the glass may shatter into pieces.
Physics full notes of class 11 ch7 short questions end.