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A student uses a cloth to give a plastic rod a positive charge - Edexcel - GCSE Physics - Question 7 - 2019 - Paper 1
Question 7
A student uses a cloth to give a plastic rod a positive charge. (i) Explain how the rod becomes positively charged. (ii) Figure 12 shows four light balls, Q, R, ... show full transcript
Worked Solution & Example Answer:A student uses a cloth to give a plastic rod a positive charge - Edexcel - GCSE Physics - Question 7 - 2019 - Paper 1
Step 1
Explain how the rod becomes positively charged.
Answer
To give a plastic rod a positive charge, the student rubs it with a cloth, which allows for the removal of electrons from the rod. As the rod is rubbed with the cloth, friction occurs, leading to the transfer of electrons from the rod to the cloth, thus leaving the rod with a deficiency of electrons. Since electrons carry a negative charge, their removal results in the plastic rod acquiring a net positive charge.
Step 2
Step 3
Explain how lightning is produced between the cloud and the Earth.
Answer
Lightning is produced due to the buildup of electric charges within the cloud and between the cloud and the Earth. The base of the cloud is negatively charged, which induces a positive charge on the surface of the Earth below it. When the electric field strength is sufficient, the negatively charged electrons from the cloud will rapidly discharge towards the positively charged Earth, creating a path of ionized air. This sudden movement of charge is what creates the bright flash of lightning we observe.
Step 4
Explain why transferring fuel can be dangerous and how the use of metal wires makes the process much safer.
Answer
Transferring fuel can be dangerous due to the risk of static electricity igniting the fuel vapors, which can lead to explosions or fires. When fuel is pumped, it can generate static electricity due to friction within the fuel pipes. To mitigate this risk, metal wires are used to ensure that static charges are safely carried away to the ground. This grounding prevents the buildup of static charges, making the fuel transfer process much safer.