Question Detail

PHY 102 Test Compilation PHY 102 20 Objective Question
Take CBT

Question

Two charged spheres repel with a force of 27.0x10-5 N when 0.1 m apart. Their total charge is 4x10-8 C. Find the individual charges.
Options
A 1x10-8 C and 1x10-8 C
B 3x10-8 C and 1x10-8 C
C 1x10-8 C and 3x10-8 C
Correct Answer
D 1x10-9 C and 3x10-9 C
Correct Answer

Option C is the correct answer.

Detailed Explanation

Let charges be q1, q2 with q1+q2 = 4x10-8 C. From F = k q1 q2/r2: q1 q2 = F r2/k = (27x10-5)(0.01)/(9x109) = 3x10-16. Solve x2 - (4x10-8)x + 3x10-16 = 0. Discriminant = (4x10-8)2 - 4(3x10-16) = 16x10-16-12x10-16 = 4x10-16, sqrt = 2x10-8. x = (4x10-8 +/- 2x10-8)/2 = 3x10-8 or 1x10-8 C. So the charges are 1x10-8 C and 3x10-8 C.

Hint

Let charges be q1, q2 with q1+q2 = 4x10-8 C.

Question Info

Course: PHY 102
Topic: Test Compilation PHY 102 20
Type: Objective
Difficulty: Not specified
Question 1230 of 1819
Previous Course Details Next