2P_Electrical Power. Joule’s law. Current supply efficiency

Long-term plan unit: Electrostatics

School:

Date:

Teacher name:

Grade: 10

Number present:

absent:

Theme of the lesson

Electrical Power.  Joule’s law. Current supply efficiency.

Learning objectives that are achieved at this lesson (Subject Programme reference)

Ø  To use the formulae of work, power and efficiency of current source in problem solving;

Lesson objectives

By the end of this section, students will be able to:

·         Derive the formula for calculation of total and lost power and efficiency in an electric circuit;

·         Can solve problems using formulae of work, power and efficiency

Assessment criteria

Understanding

Understand  Joule-Lenz's law as the amount of heat generated in a wire;

Application

Solve problems involving Joule-Lenz's law;

Analysis

Distinguish between total and lost power;

Language objectives

Subject-specific vocabulary & terminology

Power

Lost power

Total power

Power Efficiency

Useful set(s) of phrases for dialogue/writing

Values instilled at the lesson

v  Appreciation for the unique abilities of each learner.

v  Respect for other’s opinion while working in a group.

v  Lifelong learning that theories learned from our discussion could be applied also to practical life.

v  Internationalism – the students must recognize that the discovery of capacitors is made by physicists who came from different countries.

Cross-curricular links

      Visual Literacy Instruction – the students must understand, appreciate and comprehend what they have seen in the presentation and other video materials.

      *Utilization of IT in teaching and learning process.

      Mathematics-knowledge on algebra, fundamentals and higher mathematics are pre-requisites to this lesson

ICT skills

Presentation, Interactive Board

Previous learning

Grade 8: d.c. circuits; V = IR; Ohm’s Law; electrical characteristics; circuit symbols; circuit diagrams; electrical energy and power;

Course of the lesson

Planned stages of the lesson

Planned activities at the lesson

Resources

Beginning

7 min

Teacher:

-Introduces the topic of day and spelling out the learning outcome they will possess after the study.

1. Organizational moment to acquaint students with the

• The theme of the lesson
• The objectives of the lesson
• The criteria of success for the lesson
• The plan of events for the lesson

2. Start

What is power dissipated in a circuit?

Presentation

Middle

8-11 min

 12-22 min

  23-29 min

 29-38 min

(G) Group work.

Divide learners into groups and ask each group to derive the formula for calculation of total and lost power and efficiency in an electric circuit. Then, ask learners to present their works.

(T) Teacher explanation.

·         Effect of internal resistance on Power from a battery

Consider a simple circuit in which a battery of emf  and internal resistance  drives a current  through an external resistor of resistance . The external resistor is usually referred to as the load resistor. It could stand for either an electric light, an electric heating element, or, maybe, an electric motor. The basic purpose of the circuit is to transfer energy from the battery to the load, where it actually does something useful for us (e.g., lighting a light bulb, or lifting a weight). Let us see to what extent the internal resistance of the battery interferes with this process.

The equivalent resistance of the circuit is  r + R (since the load resistance is in series with the internal resistance), so the current flowing in the circuit is given by 

The power output of the emf is simply 

The power dissipated as heat by the internal resistance of the battery is 

Likewise, the power transferred to the load is 

Note that total power:

·         Electric Power Efficiency

Power efficiency is defined as the ratio of the output power divided by the input power:

η = 100% ⋅ P_out / P_in

η is the efficiency in percentage (%).

P_in is the input power consumption in watts (W).

P_out is the output power or actual work in watts (W).

(P) Pair work.

Teacher pair up weak learners with more able students and they  may choose:

ü  Intermediate level

ü  Higher level

ü  Extension level

problems.

(I)(E) Individual work.

Learners individually solve problems for power dissipated by the load and internal resistance.

Presentation

Presentation

Appendix 1

Appendix 2

Appendix 3

End

  39-40 min

At the end of the lesson, learners reflect on their learning:

-           What has been learned

-           What remained unclear

-           What is necessary to work on

Where possible the learners could evaluate their own work as well as the work of their classmates using certain assess criteria.

Differentiation – how do you plan to give more support? How do you plan to challenge the more able learners?

Assessment – how are you planning to check students’ learning?

Health and safety regulations

Differentiation can be by task, by outcome, by individual support, by selection of teaching materials and resources taking into account individual abilities of learners (Theory of Multiple Intelligences by Gardner).

Differentiation can be used at any stage of the lesson keeping time management in mind.

Use this section to record the methods you will use to assess what students have learned during the lesson.

Health promoting techniques

Breaks and physical activities used.

Points from Safety rules used at this lesson.

Reflection

Were the lesson objectives/learning objectives realistic? Did all learners achieve the LO?

If not, why?

Did my planned differentiation work well?

Did I stick to timings?

What changes did I make from my plan and why?

Use the space below to reflect on your lesson. Answer the most relevant questions from the box on the left about your lesson. 

Summary evaluation

What two things went really well (consider both teaching and learning)?

1:

2:

What two things would have improved the lesson (consider both teaching and learning)?

1:

2:

What have I learned from this lesson about the class or achievements/difficulties of individuals that will inform my next lesson?