Electric Fields & Field Lines (Cambridge (CIE) A Level Physics)

Fig 1.1 shows an electron in a uniform electric field.

Fig 1.1

State the direction in which the electron will accelerate in the field and explain why this happens.

The strength of the electric field is 2.5 pN C^–1.

Calculate the acceleration of the electron through the field.

Explain how the acceleration changes if a proton is accelerated instead.

An electron and positron are on the same straight line as shown in Fig 1.3. 

Fig 1.3

State the direction of the electric force at points

(i) A

(ii) B

(iii) C

(iv) D.

Calculate the force on the positron if it was accelerated through an electric field with a strength of 5.6 kV m^–1.

Fig 1.2 shows the positron near a negatively charged metal plate.

Fig 1.2

Sketch the field lines from the positron.

The positron is now replaced with a charge of +4e instead as shown in Fig 1.3.

Fig 1.3

Sketch the field lines of the +4e.

A potential difference is applied between two metal plates that are not parallel, as shown in Fig 1.1.

Fig 1.1

Sketch the electric field lines between the plates.

A proton is placed between the plates in Fig 1.1.

(i) Identify where the proton needs to be to experience the greatest electric force. Label this point X.

[1]

(ii) Sketch the direction the proton accelerates in at this point. 

[1]

Calculate the acceleration of the proton when placed in a uniform electric field of field strength 6.0 × 10^–2 V m^–1_.