Lesson plan_10_Ampere force. Lorentz force

Long-term plan unit:

School:

Date:

Teacher name:

Grade: 10

Number present:

absent:

Theme of the lesson

Ampere force. Lorentz force.

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

·         10.4.1.2 – to apply the left-hand rule and describe the effect of a magnetic field on moving charged particles and electrical conductor

Lesson objectives

·         understand that a force is exerted on a current-carrying wire in a magnetic field

·         explain the effects of magnetic fields on moving charges

·         describe the paths of charged particles moving in uniform magnetic fields

·         calculate the magnetic force on current-currying conductor   and a moving charge 

Assessment criteria

A student is able to

·         describe an experiment to show that a force acts on a current-carrying conductor in a magnetic field, including the effect of reversing:

–          the current

–          the direction of the field

·         use the left hand rule to predict the direction of the resulting force when a wire carries a current perpendicular to a magnetic field

·         calculate the force on a current-currying conductor   and a charged particle in a magnetic field.

• indicate the direction of current, the velocity of a charge, the direction of the magnetic field, and the direction of the magnetic force on a current-currying conductor   current-currying conductor   and moving charge

Language objectives

Subject-specific vocabulary & terminology:

Horseshoe magnet ,current-carrying conductor, Ampere’s force , strength of the field, length of conductor, left hand rule, effect of reversing, Lorentz force, circular , spiral, path.

Useful sets of phrases for dialogue and writing:

A force acts on…

To determine the direction of …

The effect of the magnetic field on….

If we change the direction/polarity/poles  of …

Values instilled at the

lesson

Collaboration

ICT skills

Use a simulators

Cross-curricular links

Math-trigonometric function, equation manipulations

Prior knowledge

Magnetic field , magnetic field lines, magnetic field strength

Planned stages of the lesson

Beginning

 Discuss the  previous homework tasks

Starter:

(T)An electric current in a conductor produces a magnetic field. 

Question: what happens with a current carrying conductor will be placed in a uniform magnetic field?

Learning objectivities of our lesson are 

–        to describe the effect of a magnetic field on moving charged particles and electrical conductor;

–        apply the rules to find the direction of these forces to the different situations

Let’s observe the following experiments and try to do a conclusion.

Middle

(P) Activity 1.Experiment and  discussion of  the results  (Worksheet 1)

Students work in pairs  to conduct an experiment to show that a force acts on a current-carrying conductor in a magnetic field, including the effect of reversing:

–        the current

–        the direction of the field

Conclusion:

If the current-carrying wire is placed in a magnetic field (whose lines of force are at right angles to the wire) then it will experience a force at right angles to both the current direction and the magnetic field lines.

 (T) Explanation

When a current carrying conductor is placed in between the magnetic poles, the conductor experience motion due to a force. This force, called Ampere’s force,  is a result of interaction of following two magnetic fields:

 a. the magnetic field due to magnet and

b. magnetic field around a current carrying conductor.

The direction of motion is perpendicular to the direction of magnetic field (north to south) and direction of conventional current in the conductor.

The strength of the force is proportional to the following four factors:

a. Length of the conductor in a field L

b. strength of magnetic field B,

c. magnitude  of the current in the conductor,

d. angle between the magnetic field lin

es and the conductor.

The force is maximum if the angle is 90 degree and minimum force if the angle is zero.

•      F_A = B I L sin θ

Fleming’s left-hand rule is used to determine the direction of this force.

Fleming’s Left hand rule: According to this rule, extend the thumb, forefinger, and the middle finger of left hand in such a way that all three are mutually perpendicular to each another.

 If the forefinger points in the direction of the magnetic field from north to south pole and middle figure points in the direction of conventional current from positive to negative, then thumb points in the direction of the force.

Make sure that the direction of current should be from positive to negative terminal of the battery that is the direction of conventional current.

Solidification

Activity 2. Solve the problems (worksheet 2).

The Lorentz Force

(W)   The topic explanation with help of  a videoclip.

The Lorentz force is acting on moving charges in a magnetic field:

(D) Use a cathode-ray tube or an e/m tube to demonstrate the effect of the force on a beam of charged particles (electrons).

Magnetic forces can cause charged particles to move in circular or spiral paths.

Particle accelerators keep protons following circular paths with magnetic force. Cosmic rays will follow spiral paths when encountering the magnetic field of astrophysical objects or planets (one example being Earth’s magnetic field).

The curved paths of charged particles in magnetic fields are the basis of a number of phenomena and can even be used analytically, such as in a mass spectrometer.

Solidification

Activity 3. Solve the problems (worksheet 3).

https://www.youtube.com/watch?v=HTTA30sEv6o

https://www.youtube.com/watch?v=BDtnSUL2Q7o

https://www.youtube.com/watch?v=tbCXaER0w-s

The left-hand rule:

www.bbc.co.uk/schools/gcsebitesize/science/triple_aqa/keeping_things_moving/the_motor_effect/revision/3/

https://www.youtube.com/watch?v=vkZtsrgso2A

Simulation

https://www.walter-fendt.de/html5/phen/lorentzforce_en.htm

NB! In English version the Ampere force is known as a Lorentz force for  current –carrying wire in a magnetic field

The Lorentz Force

https://www.youtube.com/watch?v=nRDVm5rn_2A

Force on an electron beam:

www.youtube.com/watch?v=3McFA40nP0A

End

Sum up the lesson issues.

Homework assignment

Reflection

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 :

·         the different levels of the tasks

·         the individual support.

The methods are  planned  to use :

Health promoting techniques

Breaks and physical activities used.

Points from Safety rules used at this lesson.

Reflection

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?