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Figure 1 shows the apparatus used in an experiment to investigate electron diffraction and the de Broglie hypothesis - AQA - A-Level Physics - Question 1 - 2021 - Paper 7
Question 1
Figure 1 shows the apparatus used in an experiment to investigate electron diffraction and the de Broglie hypothesis. 1. Explain how high-speed electrons are produc... show full transcript
Worked Solution & Example Answer:Figure 1 shows the apparatus used in an experiment to investigate electron diffraction and the de Broglie hypothesis - AQA - A-Level Physics - Question 1 - 2021 - Paper 7
Step 1
Explain how high-speed electrons are produced in the apparatus in Figure 1.
Answer
Part A is the heated cathode, which emits electrons when heated. Part B is the anode, which attracts the emitted electrons due to its positive potential. The potential difference provides the necessary energy to heat the cathode and produce the electrons, while accelerates these electrons towards the target by creating an electric field.
Step 2
Suggest a suitable value for $V_2$. Support your answer with a calculation.
Answer
To achieve a wavelength approximately 50% the size of an atom (about 0.05 nm), we can use the de Broglie wavelength formula: ext{wavelength} = rac{h}{p} = rac{h}{mv} where is Planck's constant, is the mass of the electron, and is its velocity. By rearranging and substituting values, a suitable can be calculated to give the desired wavelength.
Step 3
Explain how measurements made with the apparatus in Figure 1 can be used to support the de Broglie hypothesis.
Answer
The de Broglie hypothesis states that all matter exhibits wave-like properties. By measuring the diffraction patterns produced when electrons pass through a crystalline structure, we can observe evidence of wave behavior. The interference patterns are a clear indication that electrons can exhibit wavelength behavior, thus supporting the hypothesis.
Step 4