Deflection of Charged Particle in Electric Field

In this video we want to discuss the deflection of a charged particle when it moves through an electric field.

Let's take a look at this question.

deflection of charged particle in electric field question

The angle of deflection of a particle through an electric field is proportionate to its charge to mass ratio.

deflection of charged particle in electric field angle related to charge mass ratio

The higher the charge, the stronger the attraction between the particle and electric field, hence greater deflection.

The bigger its mass, more energy is required to change the direction of motion of the particle, hence smaller deflection.

1. Determine constant k

We can work out constant k using the information given in the question for 241Am+ particle where its angle of deflection is +2 degree.

deflection of charged particle in electric field determine constant k

2. Determine magnitude of deflection

We can now use constant k to calculate the magnitude of deflection for 32S- particle.

deflection of charged particle in electric field determine magnitude of deflection

Notice we ignore the sign of the charge, as it determines the direction that the particle would be deflected towards, but not its magnitude.

3. Determine direction of deflection

Am+ is deflected towards the negative electrode and angle of deflection is defined as positive in the question.

Hence S- will be deflected towards the positive electrode, and angle of deflection will be negative since it is in the opposite direction.

deflection of charged particle in electric field determine direction of deflection

Finally we can determine the angle of deflection for 32S- is -15.1 degree (Answer B).

Topic: Atomic Structure, Physical Chemistry, A Level Chemistry, Singapore

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