ASSIGNMENT NO.1 CLASS XII Q1. How much +ve and –Ve charge is there in a cup of water (250ml) Q2. If a body gives out 10^9 electrons per second. How much time is required to get a total charge of 1C from it? Q3. Can a body has a charge of 0.8 x 10^-19C? Justify . Q4. How does the speed of electron (charged particle affects (i) mass (ii) charge? Q5. Name any two basic properties of charges. Q6. What does q1 + q2 = 0 Signify? Q7. Is the force acting between two point charges q1 and q2 kept at some distance in air attractive or repulsive if q1x q2 >0 and q1 x q2 < 0. Q8. A glass rod held in hand can be charged by rubbing with it silk but a copper rod cannot be charged like this .Why? Q9. Ordinary rubber is an insulator. But the special rubber tyres of aircraft are made slightly conducting. Why is it necessary? Q10. An electron moves along a metal tube with variable cross section. How will its velocity change when it approaches the neck of the tube ? Q11. A glass rod rubbed with silk is brought near two uncharged spheres in contact with each other, inducing charges on them. Describe what happens, when (i) the spheres are slightly separated. (ii) the glass rod is subsequently removed and finally (iii) the spheres are separated far apart? Q12. Two charged spheres A and B , identical having charges qa and qb. A third charge sphere C of same size but uncharged brought in contact with first and then with second and finally removed. What are new charges on A and B?