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vii. A large ripple tank with a vibrator working at a frequency of 30 \mathrm{~Hz} produces complete waves in a distance of 50 \mathrm{~cm} . The velocity of the wave is(a) 53 \mathrm{~cm} \mathrm{~s}^{-1} (b) 60 \mathrm{~cm} \mathrm{~s}^{-1} (c) 750 \mathrm{~cm} \mathrm{~s}^{-1} (d) 1500 \mathrm{~cm} \mathrm{~s}^{-1}

### vii. A large ripple tank with a vibrator working at a frequency of 30 \mathrm{~Hz} produces complete waves in a distance of 50 \mathrm{~cm} . The velocity of the wave is(a) 53 \mathrm{~cm} \mathrm{~s}^{-1} (b) 60 \mathrm{~cm} \mathrm{~s}^{-1} (c) 750 \mathrm{~cm} \mathrm{~s}^{-1} (d) 1500 \mathrm{~cm} \mathrm{~s}^{-1}

10.2. Think of several examples of motion in everyday life that are simple harmonic.

### 10.2. Think of several examples of motion in everyday life that are simple harmonic.

10.9. At one end of a ripple tank 80 \mathrm{~cm} across a 5 \mathrm{~Hz} vibrator produces waves whose wavelength is 40 \mathrm{~mm} . Find the time the waves need to cross the tank.Ans. (4 s)

### 10.9. At one end of a ripple tank 80 \mathrm{~cm} across a 5 \mathrm{~Hz} vibrator produces waves whose wavelength is 40 \mathrm{~mm} . Find the time the waves need to cross the tank.Ans. (4 s)

i. Which of the following is an example of simple harmonic motion?(a) the motion of simple pendulum(b) the motion of ceiling fan(c) the spinning of the Earth on its axis(d) a bouncing ball on a floor

### i. Which of the following is an example of simple harmonic motion?(a) the motion of simple pendulum(b) the motion of ceiling fan(c) the spinning of the Earth on its axis(d) a bouncing ball on a floor

10.1. The time period of a simple pendulum is 2 \mathrm{~s} . What will be its length on the Earth? What will be its length on the Moon if g_{\mathrm{m}}=g_{\mathrm{e}} / 6 ? where g_{\mathrm{e}}=10 \mathrm{~ms}^{-2} .Ans. (1.02 \mathrm{~m} 0.17 \mathrm{~m})

### 10.1. The time period of a simple pendulum is 2 \mathrm{~s} . What will be its length on the Earth? What will be its length on the Moon if g_{\mathrm{m}}=g_{\mathrm{e}} / 6 ? where g_{\mathrm{e}}=10 \mathrm{~ms}^{-2} .Ans. (1.02 \mathrm{~m} 0.17 \mathrm{~m})

10.4. How can you define the term wave? Elaborate the difference between mechanical and electromagnetic waves. Give examples of each.

### 10.4. How can you define the term wave? Elaborate the difference between mechanical and electromagnetic waves. Give examples of each.

10.4. What types of waves do not require any material medium for their propagation?

### 10.4. What types of waves do not require any material medium for their propagation?

10.7. Derive a relationship between velocity frequency and wavelength of a wave. Write a formula relating velocity of a wave to its time period and wavelength.

### 10.7. Derive a relationship between velocity frequency and wavelength of a wave. Write a formula relating velocity of a wave to its time period and wavelength.

10.10. Does increasing the frequency of a wave also increase its wavelength? If not how are these quantities related?

### 10.10. Does increasing the frequency of a wave also increase its wavelength? If not how are these quantities related?

10.3. Find the time periods of a simple pendulum of 1 metre length placed on Earth and on Moon. The value of g on the surface of Moon is 1 / 6^{\text {th }} of its value on Earth where g_{\mathrm{e}} is 10 \mathrm{~ms}^{-2} .Ans. (2 \mathrm{~s} 4.9 \mathrm{~s})

### 10.3. Find the time periods of a simple pendulum of 1 metre length placed on Earth and on Moon. The value of g on the surface of Moon is 1 / 6^{\text {th }} of its value on Earth where g_{\mathrm{e}} is 10 \mathrm{~ms}^{-2} .Ans. (2 \mathrm{~s} 4.9 \mathrm{~s})

10.5. If 100 waves pass through a point of a medium in 20 seconds what is the frequency and the time period of the wave? If its wavelength is 6 \mathrm{~cm} calculate the wave speed.Ans. \left(5 \mathrm{~Hz} 0.2 \mathrm{~s} 0.3 \mathrm{~ms}^{-1}\right)

### 10.5. If 100 waves pass through a point of a medium in 20 seconds what is the frequency and the time period of the wave? If its wavelength is 6 \mathrm{~cm} calculate the wave speed.Ans. \left(5 \mathrm{~Hz} 0.2 \mathrm{~s} 0.3 \mathrm{~ms}^{-1}\right)

10.1. If the length of a simple pendulum is doubled what will be the change in its time period?

### 10.1. If the length of a simple pendulum is doubled what will be the change in its time period?

10.5. Distinguish between longitudinal and transverse waves with suitable examples.

### 10.5. Distinguish between longitudinal and transverse waves with suitable examples.

10.8. Waves are the means of energy transfer without transfer of matter. Justify this statement with the help of a simple experiment.

### 10.8. Waves are the means of energy transfer without transfer of matter. Justify this statement with the help of a simple experiment.

Example 10.3: A student performs an experiment with waves in water. The student measures the wavelength of a wave to be 10 \mathrm{~cm} . By using a stopwatch and observing the oscillations of a floating ball the student measures a frequency of 2 \mathrm{~Hz} . If the student starts a wave in one part of a tank of water how long will it take the wave to reach the opposite side of the tank 2 maway?

### Example 10.3: A student performs an experiment with waves in water. The student measures the wavelength of a wave to be 10 \mathrm{~cm} . By using a stopwatch and observing the oscillations of a floating ball the student measures a frequency of 2 \mathrm{~Hz} . If the student starts a wave in one part of a tank of water how long will it take the wave to reach the opposite side of the tank 2 maway?

10.3. What are damped oscillations. How damping progressively reduces the amplitude of oscillation?

### 10.3. What are damped oscillations. How damping progressively reduces the amplitude of oscillation?

viii. Which of the following characteristics of a wave is independent of the others?(a) speed(b) frequency(c) amplitude(d) wavelength

### viii. Which of the following characteristics of a wave is independent of the others?(a) speed(b) frequency(c) amplitude(d) wavelength

10.1. What is simple harmonic motion? What are the necessary conditions for a body to execute simple harmonic motion?

### 10.1. What is simple harmonic motion? What are the necessary conditions for a body to execute simple harmonic motion?

iv. Waves transfer(a) energy(b) frequency(c) wavelength(d) velocity

### iv. Waves transfer(a) energy(b) frequency(c) wavelength(d) velocity

10.6. A wooden bar vibrating into the water surface in a ripple tank has a frequency of 12 \mathrm{~Hz} . The resulting wave has a wavelength of 3 \mathrm{~cm} . What is the speed of the wave?

### 10.6. A wooden bar vibrating into the water surface in a ripple tank has a frequency of 12 \mathrm{~Hz} . The resulting wave has a wavelength of 3 \mathrm{~cm} . What is the speed of the wave?

10.3. A student performed two experiments with a simple pendulum. He/She used two bobs of different masses by keeping other parameters constant. To his/her astonishment the time period of the pendulum did not change!Why?

### 10.3. A student performed two experiments with a simple pendulum. He/She used two bobs of different masses by keeping other parameters constant. To his/her astonishment the time period of the pendulum did not change!Why?

10.9. Explain the following properties of waves with reference to ripple tank experiment:a. Reflectionb. Refractionc. Diffraction

### 10.9. Explain the following properties of waves with reference to ripple tank experiment:a. Reflectionb. Refractionc. Diffraction

10.4. A simple pendulum completes one vibration in two seconds. Calculate its length when g=10.0 \mathrm{~ms}^{-2} .Ans. (1.02 m)

### 10.4. A simple pendulum completes one vibration in two seconds. Calculate its length when g=10.0 \mathrm{~ms}^{-2} .Ans. (1.02 m)

10.8. Water waves in a shallow dish are 6.0 \mathrm{~cm} long. At one point the water moves up and down at a rate of 4.8 oscillations per second.(a) What is the speed of the water waves?(b) What is the period of the water waves?Ans. \left(0.29 \mathrm{~ms}^{-1} 0.21 \mathrm{~s}\right)

### 10.8. Water waves in a shallow dish are 6.0 \mathrm{~cm} long. At one point the water moves up and down at a rate of 4.8 oscillations per second.(a) What is the speed of the water waves?(b) What is the period of the water waves?Ans. \left(0.29 \mathrm{~ms}^{-1} 0.21 \mathrm{~s}\right)

10.2. A pendulum of length 0.99 \mathrm{~m} is taken to the Moon by an astronaut. The period of the pendulum is 4.9 \mathrm{~s} . What is the value of g on the surface of the Moon?

### 10.2. A pendulum of length 0.99 \mathrm{~m} is taken to the Moon by an astronaut. The period of the pendulum is 4.9 \mathrm{~s} . What is the value of g on the surface of the Moon?

ix. The relation between v f and \lambda of a wave is(a) v f=\lambda (b) f \lambda=v (c) v \lambda=f (d) v=\lambda / f

### ix. The relation between v f and \lambda of a wave is(a) v f=\lambda (b) f \lambda=v (c) v \lambda=f (d) v=\lambda / f

Example 10.2: A wave moves on a slinky with frequency of 4 \mathrm{~Hz} and wavelength of 0.4 \mathrm{~m} . What is the speed of the wave?

### Example 10.2: A wave moves on a slinky with frequency of 4 \mathrm{~Hz} and wavelength of 0.4 \mathrm{~m} . What is the speed of the wave?

10.2. A ball is dropped from a certain height onto the floor and keeps bouncing. Is the motion of the ball simple harmonic? Explain.

### 10.2. A ball is dropped from a certain height onto the floor and keeps bouncing. Is the motion of the ball simple harmonic? Explain.

10.6. Draw a transverse wave with an amplitude of 2 \mathrm{~cm} and a wavelength of 4 \mathrm{~cm} . Label a crest and trough on the wave.