Physices

Preparation of a lesson

(Teaching Physics Effectively)

Level: Terminal LS
Unit Title: Mechanics – Ch5
Lesson Title: Forced Oscillations – Resonance
 

Duration: 2 periods
I) Objective: To learn the characteristics of forced oscillations, acquire a deeper knowledge about
the phenomenon of resonance, and explain natural phenomena like earthquakes and
storms. Therefore, we need to:

• Characterize forced oscillations.
• Identify the conditions of resonance.
• Give practical examples of forced oscillations with and without resonance.

II) Major concepts:
Forced oscillations, slight damping, large damping, extremely large damping, sharp
resonance, flat resonance, exciter, resonator.
III) Materials:
Heavy pendulum. LCD projector.

I) Instructional Procedures or Activities:

a)Reminder: A review about the proper frequency of a pendulum studied in chapter 4.

b)Stimulate Students Thinking:

Then we ask students:

• After a moderate earthquake we see that in the same area some buildings are destroyed while others are not, why?
• Engineers insist a huge pendulum be setup in the bases of towers during the construction phase. Why?
• A good video is: http://www.youtube.com/watch?v=bDeswHjH1-U&feature=related  on which students watch a video of a bridge resonating to maximum amplitude before it is destroyed.

c)Set induction: A setup made of an Exciter with adjustable proper frequency, coupled to a light pendulum Resonator , forces it to oscillate. The light pendulum oscillates with maximum amplitude for only one value of the proper frequency of the Exciter. Students watch the activity on this URL address: http://www.youtube.com/watch?v=PSjchBpKK9U&NR=1

and are then invited to interpret the outcomes through team work. The results attained by the groups are then presented and a common interpretation is concluded.

d)Instructional input: The heavy pendulum (exciter) causes the light pendulum (resonator) to oscillate. The exciter imposes its frequency on the resonator. When the exciter oscillates with a frequency equal to that of the resonator, this latter enters into resonance with the exciter and oscillates with maximum amplitude. In case the frictional forces are slight, the resonance is called sharp resonance results. In case the frictional forces are significant or large enough, the resonance is called flat resonance. In case the frictional forces are extremely large then we obtain forced oscillations but no resonance, as in the case of eardrum or loudspeaker. In case of forced oscillations the resonator is sensitive to a broad range of frequencies.

The graphs corresponding to the different types of resonance are drawn on the same graph so that students may identify the difference between them.

e)Checking for Understanding:

• Random: Ask students to define: resonance, sharp resonance, flat resonance, and forced oscillations.
• Choral Responses: Ask the same questions for the entire class.

II)Independent Practice:

Ask students to explain and answer the questions (in part V-b) asked about the earthquake, towers construction, bridges construction.

III)For further examples watch:

http://www.youtube.com/watch?NR=1&v=z39p4TuDUpU

http://www.youtube.com/watch?feature=player_detailpage&v=IDi0bb0u3V8

http://www.youtube.com/watch?v=17tqXgvCN0E&feature=related

Physices

Preparation of a lesson

(Teaching Physics Effectively)

Level: Terminal LS
Unit Title: Mechanics – Ch5
Lesson Title: Forced Oscillations – Resonance
 

Duration: 2 periods
I) Objective: To learn the characteristics of forced oscillations, acquire a deeper knowledge about
the phenomenon of resonance, and explain natural phenomena like earthquakes and
storms. Therefore, we need to:

• Characterize forced oscillations.
• Identify the conditions of resonance.
• Give practical examples of forced oscillations with and without resonance.

II) Major concepts:
Forced oscillations, slight damping, large damping, extremely large damping, sharp
resonance, flat resonance, exciter, resonator.
III) Materials:
Heavy pendulum. LCD projector.

I) Instructional Procedures or Activities:

a)Reminder: A review about the proper frequency of a pendulum studied in chapter 4.

b)Stimulate Students Thinking:

Then we ask students:

• After a moderate earthquake we see that in the same area some buildings are destroyed while others are not, why?
• Engineers insist a huge pendulum be setup in the bases of towers during the construction phase. Why?
• A good video is: http://www.youtube.com/watch?v=bDeswHjH1-U&feature=related  on which students watch a video of a bridge resonating to maximum amplitude before it is destroyed.

c)Set induction: A setup made of an Exciter with adjustable proper frequency, coupled to a light pendulum Resonator , forces it to oscillate. The light pendulum oscillates with maximum amplitude for only one value of the proper frequency of the Exciter. Students watch the activity on this URL address: http://www.youtube.com/watch?v=PSjchBpKK9U&NR=1

and are then invited to interpret the outcomes through team work. The results attained by the groups are then presented and a common interpretation is concluded.

d)Instructional input: The heavy pendulum (exciter) causes the light pendulum (resonator) to oscillate. The exciter imposes its frequency on the resonator. When the exciter oscillates with a frequency equal to that of the resonator, this latter enters into resonance with the exciter and oscillates with maximum amplitude. In case the frictional forces are slight, the resonance is called sharp resonance results. In case the frictional forces are significant or large enough, the resonance is called flat resonance. In case the frictional forces are extremely large then we obtain forced oscillations but no resonance, as in the case of eardrum or loudspeaker. In case of forced oscillations the resonator is sensitive to a broad range of frequencies.

The graphs corresponding to the different types of resonance are drawn on the same graph so that students may identify the difference between them.

e)Checking for Understanding:

• Random: Ask students to define: resonance, sharp resonance, flat resonance, and forced oscillations.
• Choral Responses: Ask the same questions for the entire class.

II)Independent Practice:

Ask students to explain and answer the questions (in part V-b) asked about the earthquake, towers construction, bridges construction.

III)For further examples watch:

http://www.youtube.com/watch?NR=1&v=z39p4TuDUpU

http://www.youtube.com/watch?feature=player_detailpage&v=IDi0bb0u3V8

http://www.youtube.com/watch?v=17tqXgvCN0E&feature=related

Physices

Preparation of a lesson

(Teaching Physics Effectively)

Level: Terminal LS
Unit Title: Mechanics – Ch5
Lesson Title: Forced Oscillations – Resonance
 

Duration: 2 periods
I) Objective: To learn the characteristics of forced oscillations, acquire a deeper knowledge about
the phenomenon of resonance, and explain natural phenomena like earthquakes and
storms. Therefore, we need to:

• Characterize forced oscillations.
• Identify the conditions of resonance.
• Give practical examples of forced oscillations with and without resonance.

II) Major concepts:
Forced oscillations, slight damping, large damping, extremely large damping, sharp
resonance, flat resonance, exciter, resonator.
III) Materials:
Heavy pendulum. LCD projector.

I) Instructional Procedures or Activities:

a)Reminder: A review about the proper frequency of a pendulum studied in chapter 4.

b)Stimulate Students Thinking:

Then we ask students:

• After a moderate earthquake we see that in the same area some buildings are destroyed while others are not, why?
• Engineers insist a huge pendulum be setup in the bases of towers during the construction phase. Why?
• A good video is: http://www.youtube.com/watch?v=bDeswHjH1-U&feature=related  on which students watch a video of a bridge resonating to maximum amplitude before it is destroyed.

c)Set induction: A setup made of an Exciter with adjustable proper frequency, coupled to a light pendulum Resonator , forces it to oscillate. The light pendulum oscillates with maximum amplitude for only one value of the proper frequency of the Exciter. Students watch the activity on this URL address: http://www.youtube.com/watch?v=PSjchBpKK9U&NR=1

and are then invited to interpret the outcomes through team work. The results attained by the groups are then presented and a common interpretation is concluded.

d)Instructional input: The heavy pendulum (exciter) causes the light pendulum (resonator) to oscillate. The exciter imposes its frequency on the resonator. When the exciter oscillates with a frequency equal to that of the resonator, this latter enters into resonance with the exciter and oscillates with maximum amplitude. In case the frictional forces are slight, the resonance is called sharp resonance results. In case the frictional forces are significant or large enough, the resonance is called flat resonance. In case the frictional forces are extremely large then we obtain forced oscillations but no resonance, as in the case of eardrum or loudspeaker. In case of forced oscillations the resonator is sensitive to a broad range of frequencies.

The graphs corresponding to the different types of resonance are drawn on the same graph so that students may identify the difference between them.

e)Checking for Understanding:

• Random: Ask students to define: resonance, sharp resonance, flat resonance, and forced oscillations.
• Choral Responses: Ask the same questions for the entire class.

II)Independent Practice:

Ask students to explain and answer the questions (in part V-b) asked about the earthquake, towers construction, bridges construction.

III)For further examples watch:

http://www.youtube.com/watch?NR=1&v=z39p4TuDUpU

http://www.youtube.com/watch?feature=player_detailpage&v=IDi0bb0u3V8

http://www.youtube.com/watch?v=17tqXgvCN0E&feature=related