An electron moves into a magnetic field directed into the page, travelling vertically upward. In which direct…

Question

An electron moves into a magnetic field directed into the page, travelling vertically upward. In which direction will the electron be deflected? Show your reasoning using Fleming's left-hand rule. (Recall that conventional current is opposite to the direction of electron motion.)

Accepted Answer

## Model Answer **Given:** Electron moves vertically upward; magnetic field (B) directed into the page. **Step 1:** Conventional current is opposite to electron motion, so conventional current flows **vertically downward**. **Step 2 – Apply Fleming's Left-Hand Rule:** - Forefinger (B): into the page - Middle finger (current): downward - Thumb (force): points **towards the right** **Therefore, the electron is deflected towards the right.** *(Source: Chapter 12, Section 12.3 – Force on a Current-Carrying Conductor in a Magnetic Field)* --- ## Explanation **What examiners look for (3 marks):** 1. **(1 mark)** Correctly reversing electron direction to get conventional current direction. 2. **(1 mark)** Correctly stating which finger represents B, current, and force in Fleming's Left-Hand Rule. 3. **(1 mark)** Correct final direction of deflection. **Key tip:** The most common mistake is forgetting to reverse the electron's direction before applying the rule. Always state "conventional cur…

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