Question

12) a) A 0.030 kg plastic comb acquires a charge (electrons) of about (-1.0x10-8 C) when passed through your hair. What is the magnitude of the electric force between two such combs held 0.5 m apart after being passed through your hair? (Hint: See Example 3 in Lecture 1B on Blackboard). b) If two identical 0.030 kg comb carry one surplus electron for every 1011 electrons in each comb, what is the magnitude of the electric force between these combs held 0.5 m apart? c) What is the magnitude of the initial acceleration gained by each comb?

Answer 1

Soli- (a) Each comb has charge -1810-8 Coulomb Electric force is given by k 2, 22 ) FE (-1) x 10-8 (-1) x10a 4T E. (0.5) =) F = 0.36xlos N (6) One surplus electron for every 10" electrons mean; there is extra one è for acquiring lon electrons. I+10" - 10" It does not make any difference q =-ne = q= 10" x 1.6x10-19 - q = -1.6x108 Therefore, FE (-1,6X10"") Y TE (0.5² =) F ~ 0.92x105N if we take charge of é is 1.0x10-13 instead of 1.6x1073 the answer should be same. 2 - (c) As we know that: F=ma -> a=f Using the answer of bort (2); we get- 0.36 x 10 a = 36 x los x 105 x 102 a =) a = o.030 3 Xlor a = -) 12x10-5 m/sec² Since both the comb has equal mass. So, they have same acceleration