A polythene piece rubbed with wool is found to have a negative charge of 3 × 10−7 C.
(a) Estimate the number of electrons transferred (from which to which?)
(b) Is there a transfer of mass from wool to polythene?
(a) When polythene is rubbed against wool, a number of electrons get transferred from wool to polythene. Hence, wool becomes positively charged and polythene becomes negatively charged.
Amount of charge on the polythene piece, q = −3 × 10−7 C
Amount of charge on an electron, e = −1.6 × 10−19 C
Number of electrons transferred from wool to polythene = n
n can be calculated using the relation, q = ne
=
= 1.87 × 1012
Therefore, the number of electrons transferred from wool to polythene is 1.87 × 1012.
(b) Yes. There is a transfer of mass occur. This is because an electron has mass,
as we know
me = 9.1 × 10−3 kg
Total mass transferred from wool to polythene,
m = me × n
= 9.1 × 10−31 × 1.85 × 1012
= 1.706 × 10−18 kg
Hence, a negligible amount of mass is transferred from wool to polythene.
NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:
This question is important because it tests key concepts from the NCERT syllabus and is frequently asked in CBSE exams.
This question is based on core NCERT concepts explained in the chapter and should be revised thoroughly before exams.
(a) When polythene is rubbed against wool, a number of electrons get transferred from wool to polythene. Hence, wool becomes positively charged and polythene becomes negatively charged.
Amount of charge on the polythe...
Step-by-step explanation:
• (a) When polythene is rubbed against wool, a number of electrons get transferred from wool to polythene
• Hence, wool becomes positively charged and polythene becomes negatively charged
•
•
• Amount of charge on the polythene piece, q = −3 × 10−7 C
Students often lose marks by skipping steps, writing incomplete explanations, or misunderstanding keywords used in the question.
Stay updated with our latest educational content and study tips
Thirty is when the question starts to get raised and you’re able to do something because you know you have the experience—you know you have the responsibility. Here are some ways to consider the choice based on a realistic assessment without idealizing either aspect. Restlessness is one of those things that appears in your early … Read more
Read More
It’s not about starting over if you took a break to care for children, take care of yourself, be healthy or for any other reason. This is a realistic strategy for the recovery of skills, selection of the right job, and overcoming the resume problem. One year, three years or 10 years of a career … Read more
Read More
There’s no need to score 95% or achieve a JEE/NEET rank. You don’t need to score 95% or rank in JEE/NEET to build a solid career. A candid and pragmatic guide to the routes that actually work for students who have an average mark and what to do when faced with the options. If … Read more
Read More
AI tools, online platforms that are much cheaper than coaching centres and the changing idea of what “structure” even means have upended this argument more in the past two years than in the decade preceding it. Here’s what is really the case for 2026 – and what has actually stayed the same. If you look … Read more
Read More
Student Discussion
Regards.
Please check.
Regards
Please explain the fault in the numerical.
ADD NEW COMMENT